Eight people trapped 100 feet in the air were rescued after four hours of being stuck on a Texas roller coaster in a harrowing ordeal.

The fire department was called after riders were stuck facing upwards on the Iron Shark roller coaster at Pleasure Pier in Galveston just after 5 p.m. local time on May 28. The ride experienced a “malfunction on its initial ascent” and immediately stopped “to keep everyone safe,” according to a statement by the amusement park.

Witnesses captured the dramatic incident on video as firefighters worked to rescue riders who were stuck facing upward at 100 feet in the air.

“We had to be very careful, especially with the rescuers we had in the basket at the time,” Galveston Fire Department Chief Mike Varela Jr. told reporters in a press conference May 28.

Fire department personnel used a tower truck with its basket extended to its full length of 105 feet to retrieve the riders over the course of four hours. Varela Jr. said at the press conference that no one was injured.

“They are providing them direction on what to do, where to step, how to come down on that ladder all the way through down the ladder until they get down on the ground,” Varela Jr. said at the press conference.

The riders were identified by Houston Independent School District officials as students on a field trip organized by the charter schools Energized for STEM Academy Middle School and STEM Academy High School, according to NBC affiliate KPRC.

“We are thankful for the rescue efforts of the first responders and park personnel,” the district said in a statement.

Pleasure Pier opened in 2012, and the Iron Shark is one of the park’s marquee rides. The steel roller coaster features a 100-foot vertical lift with speeds up to 52 miles per hour, according to the park’s website. Riders are arranged in two rows with four riders in each row for a total of eight riders per car.

“The Iron Shark will attack when least expected,” the parks says in its description of the ride.

Pleasure Pier said in its statement that “a thorough inspection of the ride is currently underway.”