SAN JOSE, CALIF. – A disgruntled worker killed by police after he allegedly opened fire on colleagues felt mistreated on the job and angry about a recent suspension, according to friends and acquaintances.

Authorities say Shareef Allman, 47, gunned down his co-workers during a routine safety meeting the Plant near Cupertino on Wednesday. Three people died and six were wounded. Officials believe Allman also shot a woman in an attempted carjacking a couple of hours after fleeing the quarry.

Allman was shot and killed by police Thursday after an intense manhunt in the Silicon Valley suburbs, authorities said.

Sheriff’s officials late Thursday said they had obtained a surveillance video of Allman that was taken from a security camera that showed Allman walking with a rifle after the shooting.

Authorities have not released any details about a possible motive, other than to say the suspect was disgruntled.