An unidentified employee is comforted Thursday after a workplace shooting at the Kraft Foods plant in northeast Philadelphia. Two people were killed.

PHILADELPHIA — Minutes after a woman was suspended from her job at a Kraft Foods plant and was escorted out, she returned with a handgun and opened fire, killing two people and critically injuring a third before being arrested, police said.

The shootings occurred shortly after 8:30 p.m. Thursday inside a northeast Philadelphia plant where workers for the nation's largest food manufacturer make cookies and crackers.

About 10 minutes after the woman was escorted out, she returned in a car and drove through a security barrier before re-entering the building on foot, Lt. Frank Vanore said.

As she walked inside, she fired a shot at an employee who had followed her in and had yelled, "Hide, she's got a gun!" Vanore said. That shot missed.

The woman then shot the three victims, said police, who didn't immediately release the victims' identities or say whether they had been targeted. Officers responded and isolated the shooter in a room, and she fired a shot at them but missed, Vanore said.

Officers freed seven people who were "in a bad position" near the woman and were hiding, said Vanore, who wouldn't refer to them as hostages. The woman was apprehended about an hour after the shootings started, he said.

Investigators, who didn't say why the woman had been suspended, were working to piece together more about what led to the sequence of events. They did not identify her.

Television footage showed workers leaving the plant, which used to be known as the Nabisco factory and is about six stories tall. Police surrounded the plant minutes after the shootings, and roads in the area were detoured as officers swarmed nearby.

Dough mixer Andy Ryan, who has worked at the plant for nearly 30 years, said he was on the third floor when the sound of the shots echoed through the building.

"I heard the gunfire, and I ran," he told The Associated Press, his apron still on. "As I was running down the steps they were yelling, 'Oh, my God, there's three people shot!"'

The Philadelphia Inquirer reported about 100 people were inside the plant but had been cleared out.

Kraft said the plant would be closed until further notice and the company would provide employees with counseling.