Lightning hitting a tree caused three fires on East Ninth Street in Duluth this morning, extensively damaging one house.

The fires were reported at 4:10 a.m. Firefighters arrived on the scene to find the front of the house at 21 E. Ninth St. fully involved. That fire was causing the siding on the house at 19 E. Ninth St. to melt and burn.

Three people living at 21 E. Ninth St. escaped the burning building.

The exterior fire at 21 E. Ninth St. was knocked down but could not be completely extinguished due to a gas-line break at ground level under the deck at the front of the house. Interior operations were delayed until it was determined that there was not a danger of an explosion. After that, firefighters entered the building to attack the blaze. The burning gas under the deck burned for more than an hour after the main fire was extinguished while city crews worked to find valves to stop the flow of gas to the building.

Damage estimates for the house at 21 E. Ninth St. are placed at $60,000 for the structure and $20,000 for the building's contents. The damage to the home at 19 E. Ninth St. was limited to burned and melted vinyl siding, soffits, and window trim. This damage is estimated at $10,000.

Firefighters also found a small fire coming out the ground four houses away from the main fire scene. This fire was caused by a ruptured gas line under the tree hit by lightning. This fire continued to burn until the gas was shut off but did not cause any property damage.

After hitting the tree, the lightning traveled through an underground gas main in the street and then up through a metal tracer line on the plastic pipe leading to the house at 21 E. Ninth St. The house was on the end of a dead-end gas main, which may have been a factor in its involvement, fire official said.

There were no injuries due to the fires. A total of 28 firefighters on nine apparatus responded to the fires.