Tillicum, WA – A propane leak is responsible for the explosion Wednesday night in Lakewood’s Tillicum neighborhood, according to West Pierce Fire and Rescue spokeswoman Jenny Weekes.

The explosion happened at about 8:22 p.m. in a camper in the backyard of a residence in the 15200 block of Fern Street Southwest.

Three people who were inside the camper at the time of the explosion were sent to Harborview Medical Center in Seattle with non-life-threatening injuries. Q13 Fox news reported they were in satisfactory condition Thursday morning.

Weekes said she wasn’t sure whether the people live in the camper. It was not hooked up to a truck, she said.

Lakewood police investigated the explosion alongside West Pierce Fire officials. Police said via Twitter Wednesday that the explosion was not suspicious.