Half a dozen children were injured during a roller-coaster ride in California this weekend when it experienced a mechanical issue that caused an abrupt stop.

Six children were riding a roller coaster at John’s Incredible Pizza Company in Riverside, California, on Monday when it reportedly came to a sudden stop, forcing the child passengers to lurch forward. The cause: A rogue wheel.

The injured children suffered injuries to their noses and faces.

Ryan and Elvira Reynolds told ABC 7 that their two daughters were on the ride when it malfunctioned.

“Apparently the wheel broke off and the whole thing just stopped and all the kids bumped their heads,” Ronald Reynolds said.

“They were fine until a couple seconds later they started bleeding. My daughter and three of the other kids had blood coming out of their noses and one of the girls had a broken nose,” Elvira Reynolds said.

Capt. Tyler Reynolds with the Riverside Fire Department gave a statement to ABC 7 summarizing the incident.

“We had a kids’ roller coaster, we had a mechanical issue where one of the wheels fell off. Basically a children’s roller coaster about 5 feet off the ground,” Capt. Reynolds said. “They say it travels between 5 and 10 mph. Once that wheel fell off and came to that sudden stop, everybody was just launched forward.”

John’s Incredible Pizza Company reportedly declined to comment.

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