CREVE COEUR, Mo. – An odd combination of weather knocked out power for thousands of Ameren customers and caused several wooden power poles to catch fire.

“It’s unique in the number of these incidents in a single day,” Ameren executive Kevin Anders said.

Power poles including one near Ballas and Olive in Creve Coeur burst into flames.

Anders said it was because of “electrical tracking across insulators.”

In simple terms, this is what happened: there’s been plenty of salt applied to area roads and little rain to wash it away. Vehicles churned up that sediment, which then became airborne and settled on the insulators on power poles. That, along with a foggy light mist, combined to set off fires.

“It’s allowing electricity to be conducted across those insulators, it’s heating up the wood structure, causing it to catch fire, and it collapses the structure and causes a power outage,” Anders said.

In St. John, while crews made repairs, businesses including a McDonalds and Walgreens remained close.

Webster University and schools in the Webster School District were forced to cancel classes.

The middle school in the Ritenour School District called off school for the day, but the state has rules that say kids will not have to make it up.

“They call it ‘other circumstances,’ something like power outages or a water main break, the students are allowed to have those,” said Doug Bray, a district spokesman.

The pole fires caused an electrical surge and set off a domino of false calls that firefighters had to respond too.

“It can set off fire alarms, false alarms, trouble alarms; we’ve had reports of lights flickering in buildings,” said Maryland Heights Fire Captain Rob Daus.

Ameren officials said this does happen from year to year, but this time it was different because there were so many incidents.