Two boys were killed and two girls were injured after the off-road vehicle they were in crashed in an unincorporated area of Blythe, officials said Tuesday.

The crash occurred about 11:45 a.m. Sunday south of the 10 Freeway and east of Mesa Drive in the unincorporated Mesa Verde area of Riverside County. A 13-year-old girl driving a 2015 Polaris RZR made a left turn and the vehicle rolled onto its right side, the California Highway Patrol said in a news release.

The driver and a 9-year-old girl who was sitting in the back were wearing seatbelts and suffered moderate injuries.

Two boys, 13 and 14, were sitting on top of a back door panel with their backs facing outward without seatbelts. They were ejected from the vehicle and the RZR rolled on top of them, CHP officials said in the news release. They suffered fatal injuries.

The boys were identified by the Riverside County Coroner’s Office as Javier Castillo, 13, and Eliseo Castillo, 14, both of San Jacinto.

Drugs and alcohol are not believed to be a factor in the crash, the CHP reported.

Under the California Vehicle Code, a driver’s license is not required to operate an off-highway motor vehicle and there is no age minimum, but the driver must be able to reach and operate all controls necessary to safely operate the vehicle. Parents or guardians may not allow children under 14 to operate OHVs that don’t fit them, the code states. Further age-related restrictions apply to OHVs operated on public lands in the state.

It’s not clear if the investigation will lead to a request for charges against anyone involved.