(CNN) -- An eight-hour hostage standoff ended late Wednesday when an armed, disabled man wheeled himself out of a Virginia post office and was taken into custody, according to the mayor of Wytheville.
Initially, authorities reported five people -- three postal workers and two customers -- were taken hostage after a man entered a Wytheville, Virginia, post office about 2:30 p.m. and fired a gun. But Mayor Trent Crewe said police later believed the gunman was holding fewer than five people and that they have accounted for people they thought could have been inside.
"Apparently they ran as it was unfolding and we didn't know that for a while," Crewe said.
An unidentified witness told CNN affiliate WDBJ that he, a fellow window clerk and the postmaster were in the building when the gunman entered, but they quickly fled. He added that his supervisor was one of the hostages.
Crewe said he did not know exactly how many hostages had been in the building.
No one was reported hurt, Crewe said.
The gunman is disabled, Crewe said, adding that police told him the gunman entered the post office pushing a wheelchair. It was unclear what the purpose of the wheelchair is, Crewe said.
There were reports the man had a "device," and it appeared that his car, parked outside the office, was equipped with some type of device as well, Crewe said. He did not elaborate on what the device could be.
"The police authorities have told me they are acting on the assumption there is an explosive device of some kind in some location," Crewe said. "There is a bomb squad, in fact more than one bomb squad on site, but we cannot confirm any explosives."
The surrounding area of downtown Wytheville has been evacuated within a three- to four-block radius, Crewe said.
The suspect asked for pizza but made no other demands, U.S. Postal Inspection Service spokesman Peter Rendina said.
The gunman's motive was unclear, Crewe said. He had not identified himself but he has told police he has a military background, Crewe said. Police have yet to confirm whether the gunman has military training, Crewe said.
Agents with the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives were also on scene, Crewe said.
Wytheville is a small town in southwestern Virginia in the foothills of the Blue Ridge Mountains. It has a population of just over 8,000.
CNN's Shawn Nottingham contributed to this report.