After a fire broke out in a District Heights apartment building, three people tried to race down the stairs to escape. But the heat was too intense and the black smoke too thick.

So the three retreated to their second- floor apartment and waited until firefighters propped up ladders and rescued them from a second-floor balcony.

The blaze that caused the commotion Wednesday morning was intentionally set, Prince George’s County fire officials said. Investigators are searching for the arsonist.

The rescues were made in the 6400 block of Pennsylvania Avenue after fire officials received calls and reports of people trapped in the two-story building about 10:30 a.m., said Mark Brady, a fire department spokesman.

No injuries were reported and firefighters didn’t find anyone else trapped in the building, Brady said. Firefighters extinguished the fire in about 20 minutes. The blaze caused about $350,000 in damage and displaced 20 people.