The gunman who killed five of his co-workers and wounded five policemen at an Illinois factory was a violent felon who nevertheless obtained a state permit to buy a firearm despite being legally barred from owning one.
Gary Martin, 45, who carried his pistol to work on Friday apparently suspecting he faced dismissal from his job, opened fire after being told of his termination in a meeting at the Henry Pratt Company plant in Aurora, Illinois, about 60km west of Chicago, police said.
The dead included the plant manager, a human resources supervisor, a human resources intern and two other workers. A sixth employee and five police officers responding to the scene were wounded, and the gunman himself was slain about 90 minutes later in a gunfight with police who stormed the building.
Martin had purchased the murder weapon, a .40-caliber Smith & Wesson handgun with a laser sight, in March 2014 from a local gun dealer, Aurora Police Chief Kristen Ziman told reporters on Saturday.
Despite his criminal history, the weapon was lawfully sold to Martin two months after he was issued a state Firearm Owners Identification, or FOID card, a document used to designate people eligible to own and buy guns.
To apply, Illinois residents need only furnish a valid driver's licence, a recent photo and $US10 fee. State police then have 30 days to approve or deny the application.
Ziman said Martin's 1995 conviction for aggravated assault in Mississippi, which reportedly involved the bludgeoning and stabbing of a girlfriend, "would not necessarily have shown up on a criminal background check conducted for the FOID card."
The siege in Illinois unfolded over an hour and a half, although the gunman's victims, including the wounded policemen, were struck by gunfire in the first several minutes, police said.
Officers eventually found Martin in a machine shop at the back of the building, and he died after a short gunfight.
Among the victims were Trevor Wehner, a human resources intern who was spending his first day at the company when he was fatally shot, police and a family friend said.
Authorities identified the other workers killed as Josh Pinkard, the plant manager; Clayton Parks, the human resources manager; Russell Beyer, a mould operator and union chairman; and Vicente Juarez, a stock room attendant and fork lift operator. Their ages were not given.
A sixth employee wounded in the shooting was expected to survive, as were the five policeman struck by gunfire. At least two of them remained hospitalised on Saturday in stable condition, Ziman said.
Australian Associated Press