MIFFLINBURG -- A faulty valve in an electric water heater caused the early Sunday morning explosion that rocked a Market Street home, a state police fire marshal said Monday.

Fire marshal Norman Fedder said the blast was accidental and added that it occurred when a pressure release valve failed and caused a buildup of pressure in the water heater.

The appliance exploded in the basement of 424-426 Market St., blowing out windows, breaking cement in the basement and tearing a hole in the first floor of the building. The second story also had heavy damage.

Darlene Davis, 54, the first-floor tenant, was home at the time of the explosion. She managed to escape unharmed by crawling out a window at the back of the building with help from her neighbors.

Heather Bierly, 29, who lived on the second floor, was not home at the time.

The building is owned by 27-year-old Eric Tice, of Lewisburg. It is not known if Mr. Tice has insurance. Damage was estimated at $83,000.

Megan Owens, 26, who lives across the street from the building, said she and her husband, Joshua, 26, and their young children were waking up when they heard the blast.

"All we heard was a loud explosion," she said. "I thought maybe a car hit a house or something like that. That's kind of what it sounded like."

Other neighbors described the explosion to be much like an earthquake and said it shook their houses.

Mrs. Owens said her husband ran outside with another neighbor to see if anyone was in the building while she called 911.

"My husband and the neighbor ran over to help," she said, adding that he and the other neighbor guided Ms. Davis to the back of the house and pulled her out of a window.

She suffered only minor scratches and cuts.

Although it is uncommon for electric water heaters to overheat and explode, Brian Capp, who owns a heating and plumbing business near Mifflinburg, said they can explode when safety mechanisms do not work.

In this case, a temperature pressure release valve was found to be faulty.

Mr. Capp explained that a temperature pressure release valve allows an electric water heater to expel water and release pressure when needed. The temperature release valve works in conjunction with the thermostat. The thermostat monitors the temperature of the water heater and shuts it down when it gets too hot.