An explosion in a hot air balloon injured four passengers near Temecula early Saturday, authorities said.
One of the passengers was sent to a burn center and two transported to trauma centers, the Riverside County Fire Department said. A fourth person suffered minor injuries, and a fifth passenger was not injured.
Riverside County Fire Department spokesman Mark Annas said the hot air balloon landed safely, "and then, there was an explosion." Authorities were called about 7:45 a.m.
The Federal Aviation Administration and the National Transportation Safety Board are investigating, Annas said.