A Chicago police officer and two federal ATF agents were followed by a vehicle before the driver pulled up and someone inside it opened fire on them, a source familiar with the investigation told NBC 5.
Questions over whether or not the officers were targeted in the shooting have not yet been answered, but details continue to unfold as a police investigation continues.
A person of interest is being questioned in connection with the shooting, another source confirmed to NBC 5.
While it was unclear how exactly the person may be connected to the case, a senior police official confirmed that the person of interest was being questioned by two detectives Wednesday afternoon.
The Chicago police officer and two federal ATF agents were shot early Wednesday while working undercover, suffering non-life-threating injuries while entering I-57 in an unmarked vehicle in the city's Morgan Park neighborhood on the Far South Side, authorities said.
The shooting took place at around 5:50 a.m. on the on-ramp of I-57 at the expressway's intersection with 119th Street, blocks away from the 22nd District police station, Chicago Police Supt. David Brown said at a news conference outside Advocate Christ Medical Center, where the officers were hospitalized.
All three - a male Chicago police officer and two agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives, one male and one female - were working together in an undercover capacity when the shooting occurred, Brown said.
They were driving in the same unmarked vehicle, attempting to enter the on-ramp onto I-57, when someone opened fire on the car from the street, Brown said.
One of the ATF agents was shot in the hand, the other was shot in the arm and the Chicago police officer suffered a graze wound to the back of the head, possibly caused by a bullet or glass, Brown and Chicago Fire Department spokesman Larry Langford said.
All injuries were not thought to be life-threatening and all three were taken to Advocate Christ Medical Center, authorities said.
"We are limited in what we can say," Brown said. "There's an ongoing investigation, officers and detectives are on the scene following up on several leads but we cannot go into further details, otherwise we'd compromise the investigation at this point."
Police "don't want to give away exactly what they were doing," Brown continued, saying only that the officer and two agents were "conducting an investigation" and headed to a location when they were shot.
Further details on any potential suspects were not immediately available.
"I just want to appeal to the public: As we get more information, we will be asking you to help," said Kirsten deTineo, the Special Agent in Charge of the ATF's Chicago Field Division. "Please keep these agents and this officer in your thoughts and in your prayers."
deTineo said she could not share how long the agents had been with the ATF but said they were both "senior agents" and "not brand new trainees." Brown noted that the Chicago police officer had been on the force for "quite some time" and was a senior officer as well.
Moments after President Joe Biden landed in McHenry County, Illinois, in a suburb northwest of Chicago, his press secretary addressed the shooting, saying the administration is "closely monitoring the situation and coordinating with the Department of Justice and ATF."
"We stand ready to provide any assistance needed," Jen Psaki said. "Our thoughts go out to the to ATF agents in the Chicago Police Department officer who were wounded, as well as their families and fellow agents and officers.”
Chicago police spokesman Tom Ahern said Tuesday that eight officers had been shot in 2021 as of the day before, that number rising to 11 with the latest shooting. A total of 36 officers have been shot or shot at so far this year, Brown said Wednesday.
"I think this highlights some of the things I've been saying over the last several weeks," Brown said. "The officers are performing their jobs at the highest level. They're risking everything to protect the people of Chicago and this includes our collaboration with ATF officers."
"They are doing their part and no one would do what these officers do right now," he continued. "This is a very challenging time to be in law enforcement. But they are rising to the challenge, doing all they can and really the work that they do is extremely dangerous."
119th Street was closed in both directions between Vincennes Road and I-57 for police activity as of 6:30 a.m. In the area surrounding Advocate Christ Medical Center in suburban Oak Lawn, South Kilbourn Avenue was closed northbound and southbound between 95th Street and 93rd Street, while 95th Street was closed in both directions between Kilbourn and Kostner avenues.