Firefighters appeared to be making headway battling the flames, with forward progress stopped and containment listed at 65% by evening.
No evacuations were ordered and no injuries were reported. Dry, hot conditions were contributing to the spread, with temperatures in the 90s through the afternoon and a light breeze fanning the flames.
The flames came dangerously close to a number of homes and one house on Miramonte Court incurred extensive damage when flames broke out on the roof. Firefighters attacked the structure fire with water and were able to keep it from spreading to other homes.
The vegetation fire - named the Star Fire - began near Chino Hills Parkway and Falling Star Lane just before 2 p.m., according to the Chino Valley Independent Fire Department.
Chino Valley Fire crews were working to contain the blaze and urged people to avoid the area.
Chino Hills Parkway between Falling Star and Chino Avenue were closed to traffic.
Chino Valley Fire continues working an approximate 50-acre vegetation fire with no containment on Falling Star Lane and Chino Hills Parkway. LA County Fire and CAL FIRE are also on scene. Please avoid the area #StarFire— Chino Valley Fire (@cvifd) July 28, 2019
Los Angeles County Fire and Cal Fire also responded to the scene.