Five people were killed and multiple police officers shot Friday when a gunman opened fire in an industrial area on the outskirts of Chicago, the latest mass shooting to hit the United States.
The shooting took place at approximately 1:28 pm, at a giant manufacturing complex in Aurora, Illinois -- a small suburb 65 kilometres west of central Chicago.
Police said officers engaged in a firefight with the suspect, thought to be an employee before he was shot dead. He was identified as 45-year-old Gary Martin.
Aurora police chief Kristen Ziman said five police officers were shot. Two were airlifted to Chicago-area trauma centres.
"The other officers on the scene located gunshot victims inside the building," Ziman told a news conference, putting the death toll at five people.
Police did not release information on the officers' conditions or identify the victims.
Police said they do not know the motive for the shooting, but witnesses told local media that the gunman was a disgruntled employee.
Witnesses said they locked themselves into nearby buildings as the gunman began firing off rounds.
The aerial TV footage showed dozens of police cars, ambulances and fire trucks at the scene as officers with shields entered the complex.
John Probst, who was in the building as the shooting began but was able to escape, told the local ABC TV affiliate he recognized the gunman as a co-worker.
"What I saw was the guy running down the aisles with a pistol with a laser on it," he said. "We were just scared."
Nancy Caal, an employee of a nearby repair workshop, told the Daily Herald newspaper she and three others had heard numerous emergency sirens, and so "went and shut the front gate and locked all of the doors."
37 mass shootings in 2019
The local school district put campuses on lockdown, but students were released later in the day.
The Illinois Fraternal Order of Police lauded the wounded police officers who "willingly ran into harm's way to protect their fellow citizens and very nearly paid the ultimate price."
The White House said President Donald Trump had been monitoring the situation.
"Great job by law enforcement in Aurora, Illinois. Heartfelt condolences to all of the victims and their families. America is with you!" Trump tweeted.
The shooting comes just a day after the first anniversary of Valentine's Day shooting at Marjory Stoneman Douglas High School in Parkland, Florida, where a former pupil killed 14 students and three staff.
Nearly 1,200 children lost their lives to gun violence in the year since and there have been 37 mass shootings -- those with at least four victims, not including the assailant -- recorded already in the US this year.
Illinois Governor JB Pritzker, a Democrat, said Friday's shooting was part of an epidemic of gun violence.
"Tomorrow, the families of the victims will be less than the whole. They join a group that should not exist, and yet continues to grow," Pritzker said.
"There are no words I can offer to lessen the pain."
A coalition of gun control advocacy groups also condemned the shooting, saying it was the 198th mass shooting in the last 10 years.
"This is a horrifying reminder of how hard we have to work to prevent gun violence. Our hearts go out to every family affected by this shooting," Holly Blastic with Moms Demand Action for Gun Sense in America, said in a statement.
In a presidential message Thursday to mark the Parkland anniversary, Trump had recommitted to "ensuring the safety of all Americans."
"Let us declare together, as Americans, that we will not rest until our schools are secure and our communities are safe," Trump said.
The chief said multiple officers were wounded, including two of the first who entered the building in a manufacturing complex where the shooting occurred at approximately 1:28 pm.