Four homes under construction in Hayward burned during a blaze early Thursday morning, according to the city's fire department.
The fire, which broke out in the area of Olympic and Huntwood avenues, threatened six completed homes nearby, a Hayward Fire Department battalion chief said.
Firefighters knocked down the flames quickly, but the fire did blow out windows and trigger sprinklers inside some of the six homes that were threatened, according to the battalion chief.
Fire crews responded to the scene between 1:30 a.m. and 2 a.m.
An investigation is underway.