A preliminary investigation report from state officials claims all three injured were bystanders, but an amusement park staff member said only one was injured waiting in line while the other two were aboard the coaster.
The accident late Thursday led to three girls being hospitalized with nonlife-threatening injuries. No one fell off the roller coaster.
"The ride actually worked as it should -- it protected everybody who was on it," said Shannon Davis, a spokeswoman with the state Department of Labor, Licensing and Regulation.
DLLR inspectors found that a mechanical malfunction caused a cable to snap.
The Tidal Wave ride at Trimper's Rides & Amusements, a single-loop coaster located at the corner of South First Street and Baltimore Avenue, will remain closed and under DLLR control until the investigation is complete.
Ocean City Police spokeswoman Jessica Waters said the injured riders were a 15-year-old from Brunswick, Md.; a 15-year-old from Annapolis; and a 10-year-old whose hometown was unavailable.
Police first received a call at 9:32 p.m. Thursday for a building fire, said Ocean City Police spokesman Mike Levy, but it was soon determined there was no fire.
Dennis Ketlinger of Union Bridge, Md., was an eyewitness to the accident.
"I heard a big 'pow!' and everybody took off running," he said. "My uncle, who's 70, he was freaking (out). He was like, 'run, run!' I turned to look. I'm watching it, I see this cable snap. I'm like, 'oh my God,' and I see it whipping."
Ketlinger said the flailing cable punched a hole in the roof of a wooden structure that covers people waiting in line for the ride. As bystanders yanked open the cart doors to release the passengers, smoke and sparks surrounded them.
"Now my kids are devastated. They wouldn't sleep last night. They're like, 'I can never ride a roller coaster again,' " Ketlinger said.
Park manager Brooks Trimper said there has never been an accident of any sort on the Tidal Wave, which opened in 1985. The rest of the park will remain open during the accident investigation.