San Bernardino County Fire said the crash occurred at Cable Airport in Upland, and the three occupants were found deceased, the fire department said on Twitter.
According to preliminary information, a single-engine Beechcraft P35 crashed during departure around 6:30 a.m. local time, the Federal Aviation Administration said in a statement sent to USA Today.
The FAA and the National Transportation Safety Board will investigate the incident, the FAA said. The NTSB will be in charge of the investigation.
Earlier this month, six people were killed after a Cessna business jet crashed near the French Valley Airport in Murrieta, California.
And on July 4, a father died and his three sons were injured in a single-engine plane crash at the same airport.