The landmark 3,000-square-foot GG's Island Restaurant on Highway 111 was engulfed in flames when Riverside County firefighters arrived at 3:44 a.m. Tuesday. The building was once home to the Bananaz and Chart House restaurants.
It went to a third alarm at around 5:30 a.m. and it was extinguished at 7:28 a.m. by 55 firefighters.
Capt. Mike Smith says three firefighters suffered minor injuries.
Firefighters will be mopping up and extinguishing hot spots most of the day.
Highway 111 was closed between Country Club Drive and Frank Sinatra Drive during the fire fight.
Southbound lanes were reopened by 8 a.m. but northbound lanes remain closed indefinitely.
There is no damage estimate. The cause hasn't been determined.