Five people were hurt — including two firefighters — in an early morning Brooklyn blaze, authorities said.

The fire broke out on the second floor — and the flames extended to the third floor — of an apartment building on Tilden Avenue near East 29th Street in East Flatbush around 4:20 a.m., the FDNY said.

The blaze reached a third alarm, officials said.

Two civilians were treated on scene and another was taken to the hospital, the department said.

Two firefighters were also being evaluated on the scene, according to the FDNY.

The blaze was placed under control about two hours later.

The cause is under investigation.