KINGWOOD, Texas -

Arson investigators are checking to see what caused a fire in the 3600 block of Oak Lake Drive in Kingwood on Friday afternoon.  

Firefighters said a worker, drilled into a room containing ammunition for recreational firearms. They said it set off a series of explosions that caught the house on fire.

Houston Fire Department District Chief Mike Phillips said,

"He heard a loud explosion and the maintenance person came running out," Houston Fire Department district chief Mike Phillips said. "The house was on fire. The fire ensued in the area where the ammo was kept and we had multiple explosions that fed the fire itself."

The worker was rushed to the hospital. His condition had not been released. The owner was home when the fire started but was not hurt.

Firefighters battled the fire and the heat from the sun as well. 

Phillips said several were dehydrated after the fire. Their protective suits make it impossible for their own body heat to escape. 

"There's no way to cool off," Phillips said. "You're encompassed in all the gear. There's no way to alleviate any of the heat that you build up plus any heat you encounter in the atmosphere itself plus inside the building that's on fire."