Firefighters are swarming a blaze that broke out around 9 a.m. this morning at 731 Treat Avenue.

The green, two-story building appears to have sustained significant damage. Some of the tenants in the single-family structure, however, told Mission Local’s Julian Mark that their rooms were undamaged. The exterior staircase between the upper unit and the ground appears to be totaled.

Perhaps 18 people reside in this building. Six adults and a child purportedly live upstairs, with around 11 living downstairs.

A police officer at the scene told Mark that one woman has been hospitalized with an ankle injury. A tenant said she leaped from the burning building. Two other injuries were reported.

A 23-year-old tenant named Rafa Beralta lives in the downstairs unit with 10 other family members. “I was sleeping and there was a fire. I grabbed my cat and ran out. There was a big flame under the stairs [to the upstairs unit]. I felt the heat.”

An upstairs tenant named Herman Garcia, 51, said he noticed a fire at around 9 a.m. as well. He knocked on his fellow tenants’ doors to inform them and then, theatrically, escaped his home by leaping onto another building.

Lt. Jonathan Baxter, a spokesman for the San Francisco Fire Department, confirmed that 18 people live here, and that 15 adults and three children are displaced. He reiterated that three minor injuries have been reported, and the fire is under investigation. The fire apparently originated on the exterior of the building. This is a one-alarm fire. The SFFD is evaluating the sum of the damage.

Red Cross and other housing services will assist the tenants if they cannot expediently return to their homes.

This is a breaking story and will be updated as more information is obtained.