Two people were injured, one "traumatically," at California's Great America amusement park in Santa Clara, local news reported.
KGO-TV Channel 7 reported that a park worker was apparently struck in the head by a person riding on the roller coaster Flight Deck, formerly known as Top Gun, where riders' feet dangle in the air.
The ABC affiliate said witnesses told the station the worker was hurt when trying to get a dropped cellphone near the ride.
KTVU-TV Channel 2 reported that the worker, whose injuries were described as traumatic, was "alert and talking" when taken to the hospital.
The second person injured was a person on the ride, who suffered a hand injury, KPIX-TV Channel 5 reported.
The Top Gun ride has been in the news before. A 25-year-old man was struck in the head and killed by a rider's foot after the man apparently hopped a fence and tried to retrieve a fallen cap in 1998.