Police are investigating a fire that damaged two houses under construction in Omaha and caused a series of small explosions.

The Omaha World-Herald reports three propane tanks exploded Monday afternoon inside one house. The subsequent fire damaged a second nearby home.

Electricians working inside the first house were able to escape without injury. They then alerted workers in the second home.

The front of the first house collapsed and a side of the second home had fire damage. It was declared under control less than an hour later.

Fire officials say nobody was injured.