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

Cobb County Police officers escort workers out of the secured area of the Federal Express Ground building after a man opened fire inside the building before turning the gun on himself in Kennesaw, Georgia, April 29, 2014.

Three people were in critical condition, two of them with life-threatening injuries, after being shot by the 19-year-old gunman just before 6 am (EDT) at a FedEx warehouse near the airport in Kennesaw, Georgia, about 30 miles northwest of Atlanta, police and hospital officials said.

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

FedEx employee Liza Aiken told the Atlanta Journal-Constitution 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 this 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 after the incident 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.

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

Michael Hogland, a driver at the facility, told the paper his boss called him early on Tuesday and said a security guard was among the shooting victims.

The six patients taken to WellStar Kennestone Hospital in Marietta all had multiple gunshot 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 had been treated and were 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.

A FedEx spokeswoman extended condolences to those affected by the shooting.

"The situation is now stabilized, and we are focused on the needs of our team members and cooperating with the law enforcement investigation of this tragedy," said company spokeswoman Shea Leordeanu.