A minor electrical fire caused a major evacuation of a 17-story apartment building in Friendship Heights yesterday, as more than 1,000 people were forced from their homes when power was shut off to make repairs, authorities said.

The fire in the main electrical room on the basement level of the Irene Apartments took firefighters 20 minutes to quell about 1:30 p.m. No occupants were hurt and one firefighter suffered a minor injury, authorities said. Electrical panels in the building sustained significant damage, and power was turned off for repairs -- thus shutting off fire sprinklers and smoke-detector systems and requiring the overnight evacuation.

"Small apartment fire. A big problem," said Lt. Oscar Garcia, a spokesman for the Montgomery County fire department.

The firefighter suffered a head injury. He was treated at Sibley Hospital and released. A resident with an unrelated condition also was taken to Sibley.

After several hours, officials decided to evacuate the building, at 4701 Willard Ave. Repairs were expected to be complete by 11 last night, but there was no guarantee emergency systems would be operational. Without working alarms in the building, residents couldn't stay, fire officials said. About 60 firefighters divided the 525 apartments to tell residents to leave.

"They knocked on the door and said, 'Grab your things; you have a half an hour to get out,' " said Peter Finkhauser, who was carrying a gym bag and walking toward nearby Wisconsin Avenue with 16th-floor resident Ellen Beckwith.

"They're doing a great job," Beckwith said, "but it's heartbreaking to see these old people." The evacuation was expected to last 24 hours, officials said.

Residents toted small suitcases and rolled shopping carts filled with belongings; others took their cats away in pet carriers. Rescue officials evacuated some residents in wheelchairs and two people on stretchers.

Myrna Seidman, 66, came home from an afternoon movie and ended up in a dispute with building managers. When Seidman asked property manager Tony Perichino whether the company would pay for overnight expenses, he responded, "We're trying to find out."

"There's been no official word," Perichino said in an interview about 8:30 p.m. "Things are being worked out, and we're in the middle of assessing the damage."

The Red Cross sent more than 30 people to a Marriott hotel, and others left to stay with family or friends. Seidman said the agency told her it had used up resources for hotel rooms and was trying to arrange shelter. "I'm getting the runaround," she said. "There's no clear policy on who is supposed to do what."

Residents can call 301-652-7600 today for building information.

Staff writer Martin Weil contributed to this report.