Ringo H.W. Chiu/AP, File
California officials quickly determined an arsonist started last month's huge wildfire southeast of Los Angeles, and that two weeks earlier sparks from a vehicle produced a deadly wildfire in the far northern part of the state.
But causes for many of California's worst blazes of the past decade remain a mystery.
The Associated Press reviewed state data on the 10 largest wildfires and 10 most destructive in terms of homes and buildings burned for each year dating to 2008. Lightning was the most common cause, accounting for about a quarter of those fires, followed by incidents involving power lines.
However, investigators could not determine a cause for about a third of those fires. Experts say each is a missed opportunity to learn something new.
Krisztian Bocsi/Bloomberg via Getty Images
The soaring popularity of the video game "Fortnite" has led some parents to hire tutors to learn more about playing the game, NBC News reported.
Chuck Cohn, the founder of Varsity Tutors, which offers online instruction on a variety of academic and non-academic subjects, said his company receives between 500 and 1,000 inquiries about the game everyday.
And parents aren't the only ones working with them. Joseph Armienti, one of Varsity's tutors, said he has a mix of children and adults working with him.
“Some parents are trying to bond with their kids and have fun together,” Armienti said. “Other parents hire a tutor because their kids simply want to get better at the game as a hobby or even to be more popular in school.”
Get More at NBC News
Evan Vucci/AP, File
As Air Force One streaked across the desert sky and Las Vegas faded in the distance, President Donald Trump began seeking opinions.
The TVs on the plane, tuned as always to Fox News, carried headlines about an explosive new story: Deputy Attorney General Rod Rosenstein had suggested wearing a wire to secretly record Trump, and raised the idea of using the 25th Amendment to remove the president from office.
On the flights both to and from a Missouri rally, Trump polled staff on the plane, called his outside network of advisers and kept a careful eye on what his favorite hosts on his favorite network were recommending.
Win McNamee/Getty Images
Days before Supreme Court nominee Brett Kavanaugh is scheduled to testify before the Senate Judiciary Committee to address Christine Blasey Ford's allegations of sexual assault, a second woman has come forward alleging sexual misconduct.
Deborah Ramirez, who attended Yale University with Kavanaugh, told The New Yorker that Kavanaugh pulled down his pants and exposed himself to her while they were classmates there.
“I remember a penis being in front of my face,” said Ramirez, who says she had been drinking. “I knew that's not what I wanted, even in that state of mind.”
Get More at NBC News
Recent crackdowns targeting the sex-for-hire industry have reduced the number of commercial ads on the internet and helped fight online trafficking. But activists and police say the efforts may have had unintended consequences — landing women and girls back on the streets, where dangers also lurk.
The impact was almost immediate after the seizure of Backpage.com by the federal government in April and President Donald Trump's signature the same month on the Allow States and Victims to Fight Online Sex Trafficking Act, a law meant to hold internet platforms accountable for facilitating sex trafficking.
The number of sex ads online plummeted by 75 percent, an indication that the law was thwarting human traffickers no longer protected by the anonymity of the internet. But sex workers and their advocates say another casualty was the income of escorts who advertised online, along with the ability to vet clients better than on the street.
Jonathan Bachman/Getty Images, File
Former first lady Michelle Obama held a campaign-style rally in Las Vegas on Sunday to urge Nevadans to register to vote and cast ballots this fall, warning them that sitting out means someone else will make decisions for them.
"We get the leaders we vote for. We get the policies we vote for. And when we don't vote, that's when we wind up with government of, by and for other people," Obama told about 2,000 people inside a high school gymnasium.
The event was the first of two rallies the former first lady is scheduled to headline for the nonpartisan, nonprofit organization she co-chairs, When We All Vote.
The owner of a Texas company that sells plans to make untraceable 3-D printed guns was back in the U.S. Sunday after being arrested in Taiwan, where police say he flew after learning he was being investigated for allegedly having sex with an underage girl.
The U.S. Marshals Service said Cody Wilson, 30, was booked into Harris County Jail in Houston early Sunday and was being held on $150,000 bond.
He was arrested Friday at a hotel in Taiwan by local police. He is facing sexual assault charges in Austin, according to a statement from the U.S. Marshals service.
Jordan Strauss/Invision/AP, File
The feat will be Tuesday, when actor Will Smith celebrates his 50th birthday by bungee jumping from a helicopter. While it's been billed as a leap "in the heart of the Grand Canyon," it actually will take place over a smaller gorge on the Navajo Nation, a tribe whose reservation borders the east rim of the national park.
Getty Images/fStop, File
A California kindergartner can keep bringing a cannabis-based drug used for emergency treatment of a rare form of epilepsy to her public school, a judge ruled Friday.
The Santa Rosa Press-Democrat reported that a judge sided with the family of 5-year-old Brooke Adams.
The Rincon Valley Union School District in Santa Rosa sought to ban the ointment from school grounds because it contains the active ingredient in marijuana.
Authorities argued that allowing Brooke to use the drug at school violated state and federal laws barring medical marijuana on school grounds.
Texas Department of Criminal Justice
Authorities say bananas donated to a Texas prison turned out to have nearly $18 million worth of cocaine hidden inside the boxes.
AP Photo/Steve Karnowski
Six weeks before the 2018 midterm elections, Democrats hold a 12-point lead in congressional preference among registered voters, with nearly six-in-ten saying they’d like to see significant change in the direction President Donald Trump has been leading the country, according to a new national NBC News/Wall Street Journal poll.
The results suggest a political environment where Democrats have the clear advantage in their pursuit to win back control of Congress in November.
One pollster said that Americans are "trying to send the signal that they’re not satisfied." Another said they are trying to show "they want to shake up the status quo."
Get More at NBC News
AP Photo/Denis Poroy, File
The Trump administration has proposed rules that could deny green cards to immigrants if they use Medicaid, food stamps, housing vouchers and other forms of public assistance.
Federal law already requires those seeking green cards to prove they will not be a burden — or "public charge" — but the new rules detail a broad range of programs that could disqualify them.
The Department of Homeland Security said Saturday that current and past receipt of certain public benefits above thresholds would be considered "a heavily weighed negative factor" in granting green cards as well as temporary stays.
USGS via AP
A national park in Hawaii has reopened after being closed for more than four months because of Kilauea volcano's latest eruption, which caused widespread damage to park infrastructure and dramatically changed its landscape.
Hawaii Volcanoes National Park officials said there were no lines or waiting for visitors to catch a glimpse of the volcano that made headlines across the world when it began erupting in May. Admission is free Saturday.
The eruption destroyed hundreds of homes outside the park while changing the popular summit crater inside the park.
The national park — normally the state's most-visited tourist attraction — had been closed for 135 days as volcanic activity caused explosive eruptions, earthquakes and the collapse of the famed Halemaumau crater. Ash clouds shot skyward from the summit crater and blanketed the region in volcanic debris.
An Encinitas, California, firefighter who survived one of the deadliest mass shootings in history is now helping local first responders prepare for future active shooter emergencies.
Encinitas Deputy Fire Chief Jon Blumeyer was among the group of police and firefighters who took part in an active shooter simulation in Bonsall on Saturday.
Blumeyer was attending the Route 91 Harvest Music festival last October when a shooter started firing at the crowd.
“Once I felt that my wife was out, and our friends had gotten out, I knew people were hurt, so I had to turn around and help people,” said Blumeyer.
AP Photo/Andrew Harnik, File
She says he sexually assaulted her; he denies it. Is somebody deliberately lying?
Experts say that because of how memory works, it's possible that both Supreme Court nominee Brett Kavanaugh and Christine Blasey Ford — the woman who says a drunken Kavanaugh pinned her to a bed and groped her at a party when they were teenagers in the early 1980s — believe what they say.
And which one of them believes his or her version more strongly is no tipoff to what really happened.
"Confidence is not a good guide to whether or not someone is telling the truth," said Nora Newcombe, a psychology professor at Temple University in Philadelphia. "If they think they're telling the truth, they could plausibly both be confident about it."