Nebraska Fire Marshal deputies have determined the cause of a fire/explosion Sunday in Omaha was an act of arson.

The explosion and fire destroyed The Wardrobe Spa, 16869 Audrey St.

Investigators discovered evidence of tampering with the natural gas system in the building. The tampering was not affiliated with the utility operator, Metropolitan Utilities District, said Alyssa Sanders, a spokeswoman for the Nebraska Fire Marshal.

The Sarpy County Sheriff’s Office assisted in the investigation.

No arrests have been made yet.

The total estimated damage for the structure, not including equipment, is $350,000, Sanders said.

Sanders stressed that there is no ongoing threat to the public from the natural gas system. She said more information will be provided as the case continues.