DENVER (AP) — Security wait times are back to normal at Denver International Airport following a backlog created by a problem with the airport's train system.

Wait times reached an hour earlier Friday, causing some people to miss their flights.

The automated trains that take passengers from the main terminal to their gates stopped working at around 7:30 a.m., likely because of a software problem. Passengers were funneled through one security checkpoint and some were bused to their concourses until the trains were able to start running normally again.

The trains were run manually while the automated system was fixed but they weren't able to run as fast, and couldn't move as many passengers as they normally do. The trains began running automatically again after about an hour.

The airport is the fifth-busiest in North America.

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