Updated February 16, 2019 17:49:56

An employee of a Chicago manufacturing company has opened fire at a warehouse, killing five people and injuring several others before being fatally shot, police say.

Speaking at a press conference, local police chief Kristen Ziman said the gunman had been identified as 45-year-old Gary Martin, who was "being terminated" from his employment at the Henry Pratt Co in Aurora, 65 kilometres west of Chicago, before he opened fire.

She said officers arrived within four minutes of receiving reports of the shooting and were fired upon as soon as they entered the manufacturing warehouse, which makes valves for industrial purposes.

"May God bless the brave law enforcement officers who continue to run toward danger," Illinois Governor JB Pritzker said at the press conference.

Photo: The gunman was reportedly an employee at the company where the shooting took place. (AP: Matt Marton)

Hospitals reported treating at least seven patients from the shooting, though their conditions were not released.

Two of the officers injured in the shooting were airlifted to trauma centres in Chicago, Chief Ziman said. A sixth officer suffered a knee injury.

Officials did not confirm the total number of people injured other than the police officers.

Photo: The White House said Donald Trump was monitoring the situation. (AP: Matt Marton)

Dozens of emergency services vehicles converged on the manufacturing warehouse in Aurora after police received multiple calls at 1:24pm (local time).

John Probst, an employee at the Henry Pratt Co, told ABC7 that he ran out of the back door as the shooting unfolded.

Mr Probst said he recognised the gunman and that he worked for the company.

"What I saw was the guy running down the aisle with a pistol with a laser on it," Mr Probst said.

Aurora Mayor Richard C Irvin said it was a shame mass shootings had become commonplace.

"It's a shame that a cold and heartless offender would be so selfish as to think he has the right to take an innocent life."

The White House said President Donald Trump was briefed on the shooting and was monitoring the situation as he prepared to depart for a weekend trip to his home in Palm Beach, Florida.

Mr Trump tweeted his thanks to police officers in Aurora and offered his condolences to the victims and their families.

Presence Mercy Medical Centre was treating two patients and a third was transferred by helicopter to another hospital, spokesman Matt Wakely said.

Advocate Good Samaritan Hospital and Advocate Lutheran General Hospital each had one patient from the shooting, spokeswoman Kate Eller said.

Rush Copley Medical Centre received three patients from the shooting and all are being treated for non-life threatening injuries, spokeswoman Courtney Satlak said.

Photo: Employees were evacuated from the warehouse as police attended the scene. (AP: Matt Marton)

AP

Topics: murder-and-manslaughter, crime, crime-prevention, law-crime-and-justice, united-states

First posted February 16, 2019 14:56:13