Authorities says a teenage boy was critically hurt and two houses were seriously damaged in the explosion of an Elk Grove trailer early Thursday morning.  It happened just after 7:30 on Alpine Blue Court.

"our units arriving at the scene discovered that the incident was actually an explosion that had occured in a travel trailer that was occupied at the time of the exposion adjaecent to the home," said Deputy Fire Chief John Mikilini with the Cosumnes Fire Department.

Firefighters say they found the 16-year old victim badly burned when they got to the scene.  He was taken to UC Davis Medical Center in critical condition.  The also say it appears a propane tank in the trailer was the source of the explosion.