AYER -- Smoky conditions inside an X-ray room at Nashoba Valley Medical Center in Ayer caused alarm Wednesday afternoon and brought firefighters to the hospital to determine the cause.

Crews were called to the hospital's Radiology Department about 4:50 p.m., after a 911 caller reported a moderate smoke condition in one of the X-ray rooms.

Fire Capt. Keith Johnston said firefighters investigated and determined the smoke was emitted by a power source for one of the X-ray machines that overheated.

"No one was endangered by any means," Johnston said.

Christopher Murphy, a spokesman for the hospital's parent company Stewart Health Care, said no patients were affected by the incident.

"It wasn't in a patient-occupied area," Murphy said.