Dari Marcos said her two boys and a friend were awakened at about 11:40 p.m. by a smoke alarm in their two story condominium in the 30200 block of Via Reata.
The family and a small dog were not hurt, but the two condos were severely damaged, authorities said.
It took about 60 firefighters nearly an hour to knock down the flames, fire officials said.
The Red Cross is helping the family with housing. The other unit was under renovation.
City News Service contributed to this report.