SAN FRANCISCO (BCN) — Six people, including a pregnant woman, were displaced Friday afternoon after a fire burned two apartment buildings in San Francisco’s Richmond District.

The fire was first reported around 3:39 p.m. in the 300 block of 21st Ave., according to fire spokesman Jonathan Baxter.

The fire caused extensive damage to a three-story residential building. Another residential building located next-door sustained minor damage, Baxter said.

One man suffered a minor burn injury to his hand. He was taken to the hospital with injuries not considered life-threatening, according to Baxter.

The American Red Cross is assisting the displaced residents, fire officials said.

The cause of the fire remains under investigation, according to Baxter.