Firefighters rescued 24 riders who were stranded for hours Sunday atop a roller coaster at Six Flags America in Largo, officials said.
"All riders safely on the ground," the Prince George's County Fire Department tweeted shortly after 7 p.m.
Earlier, Fire Chief Marc Bashoor reported: "Operation going as smooth as can be expected. Patrons being evaluated."
The Joker's Jinx stalled at about 3 p.m., park officials tweeted, stranding the riders on a high curve.
"All riders are safe, upright and being helped off the ride with PGCo Fire support," officials reported.
A short time later, Bashoor tweeted that firefighters had "made face to face access with first riders." The department called the operation a "high angle rescue."
"Riders being strapped in place within each car, before cars passenger restraint can be released," Bashoor tweeted. "Then pulled 1 by 1."
Photographs on Bashoor's Twitter account show a cherry picker extending up to the top of the coaster, and what appear to be rescue workers walking along the track toward the stalled train.
Bashoor said an additional tower ladder was in place to assist. He said riders would be evaluated by emergency medical technicians before being reunited with their families.
"All riders safely disembarked from Jokers Jinx," the park tweeted. "Ride closed for now. Thanks Prince George County Fire Dept for your help!"
The Joker's Jinx, named for the Batman villain, is a 2,700-foot-long roller coaster that reaches speeds up to 60 mph, according to the Six Flags website.