The San Antonio arson unit is investigating the cause of a fire at an abandoned house on the city's East Side.

The fire started Friday around 4:30 a.m. in the 1000 block of Sherman, near the train tracks off New Braunfels Avenue.

San Antonio fire crews extinguished the fire quickly. No one was injured. 

Fire officials called in arson investigators because utilities at the house were off.

Damage estimates were unknown Friday morning.