A three-alarm fire erupted Wednesday at a Costco distribution facility in Jurupa Valley, damaging three semi trucks and the exterior of the building before crews got it partially contained.
The blaze was reported about 11:10 a.m. in one of the loading bays of the mammoth warehouse at 11600 Riverside Drive, just south of the Pomona (60) Freeway, according to the Riverside County Fire Department.
An agency spokeswoman said 18 engine crews and multiple truck companies, numbering 150 personnel, were sent to the location and encountered flames extending to three tractor-trailers.
A county fire battalion chief immediately requested mutual aid from the Ontario, Corona and Riverside fire departments.
A hazardous materials unit was also summoned to assess whether the contents burning in the trucks posed a health threat, according to reports from the scene.
The 1-million-square-foot facility was evacuated, and an ambulance was requested to stage at the site, but it was unclear whether anyone had been injured.
Crews were expected to have the fire under control by 1 p.m.
The cause was under investigation.