Seattle Fire Department officials, who responded at 5:27 p.m., said last night that the fire was caused by a short in the electrical wiring to the motor.
The blaze began shortly after the southbound Blue Train — one of two that make up the downtown monorail system — left Seattle Center for the mile-long trip to Westlake Center.
Fire crews approaching the scene were met by black smoke pouring down Fifth Avenue.
Passengers said nearly 100 people were on the train when the fire started. Thick smoke quickly filled the train as passengers — some screaming, others calm — forced their way toward the front.
The rescue of dozens of stranded passengers came on the final day of the Northwest Folklife Festival, which had attracted thousands to Seattle Center.
As hundreds of fairgoers watched, some passengers made their way down a firefighter's ladder that had been hoisted to a door in the front of the train. The system's second train pulled up alongside the damaged train, allowing some passengers to board before returning to its base at Seattle Center.
"The outcome could have been very different," said Fire Department spokeswoman Helen Fitzpatrick. "No one jumped, which is a good thing."
Power was shut off to the monorail, and the service was shut down indefinitely. About 40 passengers were evaluated for smoke inhalation and eight were taken to Harborview Medical Center, Fitzpatrick said.
One firefighter was sent to the hospital with an injured knee, she added.
All were released last night, according to a Harborview nursing supervisor.
"It really didn't take the Fire Department that long to show up," said Marlene Schwartzmann, who along with her husband, son and daughter was in the rear car of the monorail when the fire started.
"But as the inside of the monorail turned pitch black, it began feeling like an eternity."
The Schwartzmanns, of Tampa, Fla., had begun their vacation in Seattle less than 24 hours earlier. They spent several hours at Seattle Center and took a ride up the Space Needle yesterday before hopping on the monorail back to Westlake Center. They were the last ones on the train and were jammed into the back car, standing.
Holly Schwartzmann, 15, said she heard a pop and saw a spark that appeared to be coming up from the floor near the window. The lights immediately went out, her mother added.
"Everyone began pushing forward," Marlene Schwartzmann said. "It felt like 100 to 150 people in there. It was pitch black."
As they hovered on the tracks in the burning train, "People were looking up taking pictures," Holly Schwartzmann said.
Her father added: "You look down, and you see all those people looking up at you. You can't jump, it's too high. You feel trapped."
His wife added: "I'd say this is the highlight of our vacation. We're lucky it's a happy ending."
The proposed Green Line monorail will be required to have emergency escape walkways along its 14-mile length.
The monorail was built in 1962 for the Seattle World's Fair. The two trains have traveled more than 1.8 million miles on the one-mile stretch of tracks. The system carries more than 2 million passengers a year.
The most serious accident in the monorail's 42-year history was in 1971, when the braking system on the Red Train failed, sending it crashing into a steel girder at the Seattle Center station. Twenty six people were hurt.
The monorail occasionally breaks down, and passengers usually transfer to another train that pulls alongside. But fire ladders are sometimes used, including twice in 2002.
Construction of the monorail cost $3.5 million, and it was built in 10 months. Its supporting structure required 15,000 tons of concrete. Each train rides on 16 tires and each has 24 more tires suspended sideways to hug the rail.
Seattle Times reporter Lornet Turnbull: 206-464-2420 or email@example.com
Also contributing: Warren King: 206-464-2247 or firstname.lastname@example.org
Mike Lindblom: 206-515-5631 or email@example.com.