A fire broke out on the tenth floor of the Watergate East building late Wednesday night, sending one firefighter to the hospital for heat exhaustion.

D.C. firefighters responded to 2500 Virginia Ave. just before 10 p.m., D.C. Fire and EMS spokesman Peter Piringer said. The grease fire was contained to one apartment, which a firefighter on scene said was badly damaged. Though the blaze did not spread, smoke billowed throughout the building, causing damage to other units, the firefighter said.

The flames were contained and put out before 11 p.m., but the stifling heat continued to cause problems for the more than 125 firefighters and police officers who responded to the scene.

One firefighter was taken to the hospital to be treated for heat exhaustion and at least three elderly Watergate residents were taken out on stretchers — they later returned on foot to the complex — but none of the injuries were serious, Piringer said.

“We’re just making sure all the residents are cared for, one way or another,” he said.

The damage to the apartment and the surrounding units was significant, one firefighter on scene said. Piringer said because the Watergate is a high-end complex, the damage will likely be costly.

“It potentially could be significant,” Piringer said.

He said the department is now downsizing units but will continue to have units on scene for at least another hour.

The Watergate development is listed on the the National Register of Historic Places.

Priya Anand contributed to this report.