Denver International Airport fell into disarray Friday morning after a blown train tire caused power-line damage to one of the rails, crippling the system and causing hours-long delays, according to a spokeswoman.

Thousands of passengers created a line that spilled outside as only one train was available to move the crush of weekend travelers from the security checkpoint to the gates. 

“It was a domino effect that started initially with the train, then moved back through the TSA security checkpoint,” said spokeswoman Alex Renteria. “Even when the trains were cleared, there was a severe residual backup on the security line.”

Just after midnight Friday, a breaker trip suddenly stopped four trains with about 200 people onboard, according to a DIA release. Passengers pulled the emergency handles and left the trains to the tunnel walkways, where they were escorted by emergency personnel. 

Maintenance workers discovered a blown tire on one of the trains caused it to sink, damaging about 100 feet of rail line. 

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Alstrom, the company that manages the trains, finished repairs mid-morning, an airport news release announced shortly after 10 a.m. Friday.

Though no statistics on train outages were available, Renteria said delays of more than 5-to-10 minutes for train issues are rare. 

“Those trains are moving 24 hours a day. Anything that operates that much, something is going to need to be fixed or replaced,” she said. “It’s usually addressed in preventative maintenance, but there are instances.” 

Officials vowed later Friday, after the line was repaired, to find different ways to move passengers to the gates. 

‘We recognize how impactful these delays are and we apologize for the frustration this has caused,” officials said in a statement. “We are committed to exploring options to provide alternate ways to move passengers between the terminal and concourses and improving our process when incidents like this occur.”

There were discussions when the airport was built 24 years ago of having walkways to all the gates, as opposed to just A. The only way to get to gates B and C is via train.

If the trains are out for extended periods, there is the option of routing passengers through the security checkpoints before the A gates walkway, then bussing them to the B or C gates, Renteria said. 

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But so many people had backed up at the Level 5 checkpoints, it would have been chaotic to move them all to Level 6 walkway, she said. 

“It was hundreds of people by then … we would have deployed the busing if we knew it was going to be a greater challenge,” Renteria said. 

Pictures and videos on Twitter showed passengers cramming onto the trains of the one line that remained operational throughout. 

“This is an uncommon occurrence, and we are working with our teams to ensure we maximize our support for passengers during this time,” according to the early Friday release. “We will have more employees onsite to support passengers and will also make overhead announcements in the terminal.”