A fire forced some residents out of their Southwest Side apartments late Sunday night.

The fire, believed to have been sparked by a water heater, started in the first floor of an apartment complex in the 300 block of Cropsey Avenue around 10:30 p.m.

Firefighters arrived to heavy smoke spilling from the apartments and had to rescue a woman who was trapped in a second floor bedroom.

Firefighters used a ladder to get the woman to safety and also saved the woman's dog.

Fire officials said a second crew responded to help put out the fire. No injuries were reported and damage to the apartment building was estimated at $20,000, San Antonio fire officials said.

An official cause had not been determined as of 7 a.m.

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