Firefighters and Iowa Department of Natural Resources officers responded to the blast around 6:50 p.m. Sunday on the northeast part of the lake.

The department says two of the four aboard were taken to a hospital in nearby Omaha, Nebraska, for treatment of their burns: 33-year-old Joshua Juranek and 33-year-old Kimberly Red. Both live in Bellevue. It’s unclear whether the others on the board were injured.

The explosion is being investigated.

Department officials also say a 9-year-old girl was hospitalized earlier Sunday after she was injured while tubing in Lake Manawa. She’s expected to make a full recovery. Her name hasn’t been released.