Mike Perry-KTVB

Lisa Grow of Idaho Power holds up a hot tap stirrup, the type of electrical connection that failed Monday and ignited a wildfire that destroyed ten homes and damaged nine more in a southeast Boise neighborhood Monday.

BOISE -- Boise Fire investigators said Thursday that an electrical connection on a powerpole, called a hot tap stirrup, arched causing molten metal to fall to the dry grass below, igniting a wildfire that took only minutes to burn ten homes and damage nine others in a southeast Boise neighborhood Monday.

Lisa Grow, vice president of delivery operations and engineering for Idaho Power, said during the storm that blew through Boise Monday evening, just before 7 p.m. a tree branch fell into a powerline along Boise Avenue about five miles from the fire scene. That caused a break in the power distribution, forcing a stronger current to the hot tap stirrup miles away.

She says the 50 mph winds, plus the extra current, caused the arch that ignited the fire in the Oregon Trail Heights subdivision. The last time the connection was inspected was in 2006. According to Idaho Power, they are inspected every three years.

LaMont Keen, President and CEO of Idaho Power, said it was a combination of a lot of events that happend to cause the failure.

"Our preliminary investigation also suggest that a piece of our line hardware was a factor in this accidental, but devastating chain of events," said Keen.

One person died in Monday's fire. She has been identified as 56-year-old Mary Ellen Ryder, a Boise State University linguistics professor. The Ada County coroner said it will take up to three weeks to determine how she died.

Keen says Idaho Power is continuing to cooperation with fire officials in their investigation and will work to help those affected by the fire.

"We are going to be looking at all our practices. They are general utility practices that we follow, that most utilities in the industry follow, so we take those very seriously, but we are going to be looking, we want this lesson to be learned, we don't want this to be in vain. We will be looking at all our procedutes and practices and changing to the extent we can improve things, we will," said Grow.

Boise Fire Chief Dennis Doan called Monday's fire the "perfect storm" fueled by hot, dry conditions, high winds and shake roof tops. He said the quick actions of firefighters and police prevented this tragedy from becoming much worse. He also said it highlights the need for defensible space around homes in these types of areas.

If you want to help those affected by Monday's fire, the Boise Fire Department asks that you make a cash or gift card donations to their Burn Out Fund.

Over the last two days, they've received three truck loads of clothing and lots of food, what's really needed are store or restaurant gift cards and cash.