KXAN-TV reports the fire, which broke out around 6 a.m. Thursday, caused about $350,000 in damages. No injuries were reported.
Austin Fire Department spokesman Palmer Buck says the apartment complex didn't have any sprinklers.
A shelter for residents displaced by the blaze has been set up at an area Methodist church.
Officials say the complex is about 30 years old and in the past two decades, firefighters have responded to two to three blazes at the structure.
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