The fire was reported near Merwin Street and Alessandro Boulevard around 8:30 p.m. and had spread to 175 acres by around 11 p.m. according to CAL FIRE Riverside officials.
A vegetation fire was reported in the 1500 block of Burton Mesa around 1:30 p.m. and had grown to nearly 300 acres by 6 p.m., prompting authorities to evacuate approximately 1,200 people in surrounding areas.
A department spokesperson told CBS2/KCAL9 personnel were dispatched to the 3100 block of South Coldwater Canyon at Mulholland Drive at 5:38 p.m. Wednesday.
Fire crews have managed to contain a blaze that ignited in South Pasadena Sunday night.
Firefighters and water-dropping helicopters are attacking a 5-acre brushfire near the city of Santa Clarita north of Los Angeles.