The blaze erupted shortly after 9 a.m. Thursday in the 500 block of Anita Street, just east of Broadway and south of Orange Avenue, according to the Chula Vista Fire Department.
No one was inside the small residence at the time of the arrival of firefighters, who were able to extinguish the flames in about 15 minutes, CVFD Capt. Josh Sanders said.
Sanders said the blaze did not injure any residents or emergency personnel, and it caused no monetary losses except to the damaged mobile home. It did, however, kill a pet cat, OnSceneTV reported.
The American Red Cross was summoned to help the displaced residents arrange for interim shelter.
The cause of the blaze remained under investigation as of mid- afternoon, the fire captain said.