An alarm for a suspected chemical leak at the Philadelphia VA Medical Center forced an evacuation for about an hour Sunday, according to the Philadelphia Fire Department.

Firefighters responded to an alarm at the center, 3900 Woodland Avenue, shortly after 5 p.m. warning that ethylene oxide, a toxic gas used by the facility to sterilize equipment, may have leaked and tripped internal sensors in the basement. About 100 people were evacuated to the lobby of the building while a hazmat team was called, said Captain William Dixon of the fire department.

By 6 p.m. the situation was reported contained and the evacuation ended, Dixon said. According to the VA, ethylene oxide had not been used at that facility since last year and the alert was a false alarm.

"There was never any danger of a health risk to patients, staff or visitors to the facility," said Fern Billet, a spokeswoman for the hospital.

An investigation is underway to determine why the alarm was triggered, she said.