A gunman opened fire inside a sprawling a Safeway Inc.warehouse Sunday, killing one person and wounding five others -- two critically -- before he was killed by police.

Several fires also were set inside the distribution center a few miles northeast of downtown along busy Interstate 70, authorities said. The fires, which engulfed merchandise inside the warehouse including paper products, were out by Sunday night.

More than 150 employees were forced to evacuate, Police Chief Gerry Whitman said, and dozens of officers were called in to seal off the building.

"I've never been through anything like this," said Scott Stroman, a meat department employee who has been on the job less than a month. "Other employees came running up and said `Hey, let's get out of here!"'

Police did not immediately confirm the gunman's identity but police spokesman Sonny Jackson said at least one 911 caller named employee Michael Ford as being involved.

A Safeway spokesman, Jeff Stroh, said Ford worked filling orders in the produce department and was employed at the center for more than a year.

Whitman said there was no reason to believe there was more than one suspect, though the investigation was expected to continue Monday.

Police received several 911 calls reporting the shooting by 3:12 p.m. About an hour after entering the warehouse, officers found the suspect and he shot 38-year-old SWAT officer Derick Dominguez with a handgun in the left hip, Whitman said. Dominguez also suffered a broken leg.

An officer then shot and killed the suspect, Whitman said.

As officers swept through the 1.3 million-square-foot center, they found another dead victim.

By late Sunday, two victims were in critical condition, two others, including Dominguez, were in serious condition, and one had been released from Denver Health Medical Center, hospital spokeswoman Benny Samuels said.

Denver Fire Chief Larry Trujillo said multiple fires were set in one area of the building and one fire was set in another area.

Stroman said his wife and six children kept calling him after hearing about the shootings. He said it was strange to think it could happen at Safeway.

"Where I work, everybody gets along," he said.

Stroh said parts of the warehouse would reopen Monday and that store officials had contacted grief counselors for employees. The company planned to evaluate its safety policies, he said.

"Whenever workplace violence occurs, you really have to take a step back and look at what you're doing," Stroh said.