Howard County firefighters arrived at the 9700 block of Tiger Lily Path about 5:45 a.m. to find an apartment building on fire, heavy smoke and flames visible.
Residents of the third floor, where the fire was strongest, had already gotten out. After evacuating the rest of the building, firefighters were able to get the fire under control by 6:30 a.m. and completely extinguished by 8 a.m.
The fire displaced about 40 people, officials estimate. One firefighter was treated for heat exhaustion.
Officials are investigating to determine what started the fire.