Of all the things you’d think could go wrong on a roller coaster, hitting a tree isn’t usually high on the list. But it will be for the 22 coaster riders who were left stranded after their cars derailed because of arboreal interference.

KTLA reports that the incident happened around 6 p.m. on Monday night at Six Flags Magic Mountain in Valencia, CA. Apparently a pine tree next to the Ninja roller coaster had fallen onto the track and was blocking the track.

The Ninja is a suspended roller coaster, meaning the riders are hanging below the track. When the first car collided with the fallen tree, it derailed and dangled about 20 feet above the ground. The other cars in the affected train appeared to have remained on the track, but all the riders were left waiting for assistance from emergency crews.

It took several hours for Los Angeles County firefighters to safely rescue all of the stranded coaster passengers. The four riders in that first car were treated for minor injuries. Two were taken to the hospital as a precaution, a rep for the park told KTLA.

The Ninja, which has been operating for more than 25 years, is temporarily out of operation pending a “thorough inspection of the area,” says the park rep.

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.