While taking a moment to eat dinner, Waldorf Volunteers and area fire/EMS departments responded to the 2500 blk of Mattawoman-Beantown Road for a reported "structure fire" at 6:30 p.m. The caller told our 911 center they heard an explosion and fire coming out of the bedroom. A very short time later, CCSO arrived along with Waldorf Chief 3A (Mills) confirming smoke coming front door. E33 made quick work of the fire located in the 2 rooms with assistance from E11, T1, TK825. Battalion Chief 12A (Durrer) "command", 28 volunteers from our county were on scene, 15 members from PGFD responded as "mutual aid companies". Cause of this emergency incident was a malfunctioning space heater in the bedroom, the "explosion" was a result of oxygen equipment in the bedroom. Fire Marshall Office notified and Red Cross notified to assist family