Three of the four passengers in the single-engine Beechcraft Bonanza suffered minor injuries and were able to get out of the plane, which crashed about 1:25 p.m., according to firefighter Dan Horton.
The fourth suffered "moderate to serious" injuries, Horton said. All were transported to a local hospital.
Five people were initially thought to be onboard the plane, which took off from Chino Airport and was on its way to Camarillo Airport when it crashed at Wells Cargo Self Storage at 450 Camarillo Center Dr., Horton said.
It was unclear why the craft went down. The cause was still under investigation.
Nine structures at the storage facility were damaged.
At least 20 fire engines were on the scene battling a large fire that was still raging nearly three hours after the crash.
- Staff photographer Mike Baker contributed to this report.