Northgate Fire

Firefighters respond to an explosion at an apartment building under construction on Venture Way in the Northgate development in northeast Pocatello on Thursday afternoon.

POCATELLO — Authorities believe a gas leak was likely responsible for a Thursday afternoon explosion that caused extensive damage to an apartment building under construction in the Northgate development, located in the city’s northeast corner.

Construction workers reported hearing an explosion in the building on Venture Way, across from the Portneuf Wellness Complex, at 3:35 p.m., according to Ryan O’Hearn, assistant chief of operations.

O’Hearn said there was significant damage to one of the building’s walls.

The building was unoccupied and there were no injuries, O’Hearn said.

“I think it’s going to require some significant repair. I don’t think it’s going to be a total loss,” O’Hearn said.

O’Hearn said the preliminary investigation points to a gas leak as the cause of the explosion, but it’s unclear what caused the leak or what ignited the gas. He said investigators will conduct further testing to determine what failed.

Shortly after the explosion was reported, three fire engines and an ambulance were on the scene and firefighters had cut a hole in the building’s roof to provide access to spray the interior. O’Hearn said there weren’t flames within the structure, but there were some smoldering hot spots.

O’Hearn said the building’s interior was mostly finished and was at the point that fixtures and appliances were being installed.