A Thursday afternoon fire displaced 55 people from two six-unit apartment buildings near the Sonoma County Fairgrounds in Santa Rosa because of fire and smoke damage as well as firefighters cutting power to the buildings, a Santa Rosa fire official said.

The fire was reported at 2:42 p.m. when numerous people began calling emergency dispatchers to report the blaze in a single-story apartment building on Aston Avenue west of Hendley Street, dispatchers said.

Windows were exploding as the flames quickly spread into a common attic shared by all six units. The fire caused extensive damage to four of the units and smoke damage in the other two, Assistant Santa Rosa Fire Marshal Paul Lowenthal said.

Power was cut to six units in an adjacent building, as well, and all 12 units were rendered uninhabitable, he said.

Residents were being offered shelter at the First Presbyterian Church, 1550 Pacific Ave. Lowenthal said up to 25 people might utilize the shelter.

Later Thursday, Local 1401 of Santa Rosa Firefighters delivered pizzas to the families.

The cause of the fire was under investigation.