KENNESAW, Ga. - A FedEx package handler with a shotgun opened fire at a shipping facility outside Atlanta early Tuesday, injuring six people before killing himself, apparently with his own weapon, police and hospital officials said.

Three people were in critical condition after being shot by the 19-year-old gunman just before 6 a.m. at a FedEx warehouse near the airport in Kennesaw, about 30 miles northwest of Atlanta.

The shooter, identified as Geddy L. Kramer of Acworth, drove up to the security guard shack at the warehouse and shot the guard before entering the warehouse, where he shot five other people, police said.

"It was chaos," said David Titus, a FedEx truck driver. "Everyone was running, ducking and hiding, trying to get out of there."

Liza Aiken told the Atlanta Journal-Constitution that she was correcting addresses on packages when she saw a colleague dressed in black and armed with a knife, gun, and a cartridge belt strapped across his chest.

"He had bullets strapped to his chest like Rambo," she told the newspaper. "He looked like he was heading into war."

Authorities searching the building found a Molotov cocktail that appeared to have been left behind by the gunman, said Cobb County police spokesman Michael Bowman. No motive was given for the attack.

The gunman's father, Scott Kramer, released a statement expressing the family's condolences to the victims.

"Our prayers are for their complete and speedy recovery. Our thoughts are also with all the workers at FedEx who were affected by Geddy's actions. We make no excuses for his actions and are shocked and devastated by them. There really are no adequate words at a time like this," Kramer said.

Aiken said she previously had reported the man to her superiors after he pointed a work laser at her eye.

The six patients taken to WellStar Kennestone Hospital in Marietta all had multiple wounds that appeared to be from a shotgun, Dr. Michael Nitzken said at a news conference.

Two men, 28 and 22 years old, as well as a 52-year-old woman were listed in critical condition. Another 28-year-old man was stable, while a 42-year-old woman and 19-year-old man were treated and being released, Nitzken said.

Hundreds of police from multiple agencies converged on the scene after the shooting, and employees escorted from the facility in a bus tearfully reunited with family members at a nearby skating rink.

This article contains information from the Associated Press.