FARMINGTON, Maine (AP) The last of the firefighters injured in a deadly building explosion in Maine has been released from the hospital.

Maine Medical Center said Sunday that Capt. Scott Baxter has been discharged to a rehabilitation facility. The explosion destroyed the LEAP Inc. building in Farmington and hospitalized six firefighters.

Another firefighter, 68-year-old Capt. Michael Bell, was killed in the blast. The Portland Press Herald reports that LEAP maintenance manager Larry Lord was also injured and is being treated at a hospital in Boston.

The State Fire Marshal’s Office found that propane leaking from a line under a parking lot caused the explosion. It’s still undetermined what caused the leak itself or the spark that led to the blast.