A fire Saturday morning at a Bethesda apartment building displaced as many as 1,500 people, officials said.

Six people were taken to a hospital for smoke inhalation, and a firefighter was treated for heat exhaustion, Montgomery County Fire and Rescue Service Battalion Chief Michael Leigh said.

The fire occurred at 5225 Pooks Hill Rd., a high-rise residential building off Rockville Pike, near the Capital Beltway. Firefighters responded to a call about smoke on the upper floors about 9 a.m. Saturday, Leigh said. He said the fire was under control by midday.

Between 1,100 and 1,500 residents were displaced from one of the two towers — each with 550 units — Leigh said.

Officials said the fire involved the power feed to the apartment complex. Photos provided by the fire department showed severe damage to the building's electrical room. Leigh said transformers connected to the north building of the complex caught fire.

Some residents who walked down the stairwells were treated for smoke inhalation, and elderly residents were being evaluated early Saturday afternoon, according to authorities.

Residents of the south tower of the Promenade apartment complex evacuated during the fire and were allowed back inside by early afternoon. Leigh said residents in the north tower will be allowed to pick up personal belongings and medications from their apartments but cannot stay overnight, because the building has no electricity or water.

The American Red Cross worked to set up a shelter for residents.

The fire department tweeted Saturday afternoon that damage to the building was estimated at $1 million. About 140 firefighters responded to the call.