A helicopter crashed near the Greek Theater in L.A.'s Griffith Park, according to the Los Angeles Fire Department and media outlets.
The helicopter was on a routine flight from Redlands, had circled Santa Monica, and was preparing to return to the Inland Empire when it experienced mechanical problems, L.A. Fire Department spokesman Jamie Moore told the L.A. Times.
The pilot was forced to make a hard landing, then helped the three passengers exit the craft, and firefighters arrived soon after.
L.A. Fire Dept. spokesman Eric Scott told CBS 9 that 9-11 calls began pouring in at around 2:30 from bystanders. When paramedics arrived, he said, they found four people with minor injuries.
"I was told there was 3 people aboard the aircraft that suffered minor injuries," Scott said.
A park ranger nearby also suffered minor injuries from heat exhaustion, Scott told the station.
The helicopter is registered to Mile High Rotors LLC based in Colorado, and records show it has a valid airworthiness certificate, the Times reports.
It's not yet clear why the helicopter might have crashed, but the FAA tells the L.A. Times they'll investigate.
This story has been updated.