Chicago "avoided tragedy" on Monday afternoon after police officers arrested a man who opened fire at the Jesse Brown VA Medical Center on the city's West Side, FBI Special Agent in Charge Jeffrey Sallet said.
According to a spokesperson at the hospital, located at 820 S. Damen Ave., staff were told to shelter in place at around 2:18 p.m.
The suspect, who was armed with an assault rifle, shot at the building initially, and then went inside the hospital, police said at a press conference.
Authorities said the suspect fired both inside and outside but declined to answer just how many shots were fired.
Within 30 seconds of the suspect entering the building, VA police officers "mitigated the threat," Special Agent Sallett said, along with federal agents, CPD, and a SWAT team.
No injuries were reported.
The facility was given the "all clear" Monday evening, Chicago police confirmed on Twitter.
In addition, CPD later confirmed they've “had contact with the suspect in the past.”
One witness told NBC 5 he was sitting by the cafeteria area when he saw people running.
"So I walked toward the pharmacy area and a gentleman came walking past me with that big gun," Oliver Robinson said.
Another witness said he's frustrated with the number of incidents that have sparked lately in the area and abroad.
"I’m upset that we’re starting to get this so regular," Hubert Evans said. "I mean almost – you don’t want to believe it. So you hesitate for a minute and think ‘is somebody joking?’ but with people running, you’re not gonna wait and think about it."
The incident remains under investigation by the U.S. Attorney's Office. Since the hospital is a federal facility, any action taken is being looked at from a federal persepctive, officials said.