AUBURN – Fire officials Tuesday were investigating a blaze that started in an abandoned underground bunker at the Auburn-Lewiston Municipal Airport.

Nobody was hurt in the 1:30 p.m. fire, but crews were forced to close part of Hotel Road as trucks made their way to the scene.

The cement bunker, used to store ammunition in the 1940s, is near one end of the airport runway, roughly 25 feet from Kittyhawk Avenue.

Firefighters quickly subdued the flames, then began searching for the source of the fire. The cause was unknown Tuesday night.

Investigators said the cement tunnel was supposed to be unused. However, there were signs inside the bunker that someone had been using the space. Fire officials said items found in the tunnel indicated that one or more people had recently been in the bunker.

The fire remained under investigation.