Fire crews are battling a fast-moving fire on top of Loma Prieta in the Santa Cruz Mountains.
The blaze was reported in the area of Loma Chiquita and Loma Prieta roads in Los Gatos at about 2:44 p.m., according to the Pulsepoint phone application.
The evacuations are along Summit, Madonna and Croy Ridge roads. More than 300 structures are threatened, at least one house has burned, and flames are moving south.
Multiple air tankers and helicopter units from fire and police agencies throughout the area have been called to the site.
Cal Fire Chief Matt Streck said there are about 200 homes being evacuated in the Loma Prieta area and that they are using the reverse 911 system to alert residents. In San Jose, officials closed Alum Rock Park for all of Tuesday, citing the fire danger from the heat. Check back later for updates to this story.