An accused bank robber being treated at a Virginia hospital grabbed a security guard’s gun and fled in his gown and bare feet early Tuesday, authorities said. The hospital was locked down while police hunted for the fugitive.

The prisoner, identified as Wossen Assaye, overpowered the guard at Inova Fairfax Hospital at about 3 a.m. ET, NBC Washington reported. A shot was fired during the struggle, but nobody was injured, authorities said.

In the hospital, staff members were hiding in back rooms and hallways, NBC Washington reported. Police in Fairfax described Assaye as armed and dangerous. They warned people in the area to be alert to their surroundings.

Kent Knoff, who works at a nearby Exxon station, told NBC News that roads were closed around the hospital. “There are police cars everywhere,” he said.

Assaye was being held by Alexandria City on federal charges for armed bank robbery, and he had been taken to the hospital after trying to hurt himself, police said.

He has an “extensive criminal record” and a history of violence and poses a “serious risk to the community,” according to a 2012 Virginia parole board document. The document said that he committed robberies and burglaries.

Public records show a rap sheet dating to 1972 for a Wossen Assaye, including a breaking-and-entering charge in 1998 and a purse-snatching conviction in 1994, for which he was given a recommended sentence of a year in jail.

NBC News’ Jason Cumming, Alexander Smith and Christopher Nelson contributed to this report.