Some Ameren customers in Sherman, Williamsville and areas of Springfield were without for a few hours Thursday morning into the afternoon.

Sherman was the hardest hit area, Springfield had more than 600 customers affected according to Ameren’s outage map.

Spokeswoman Marcelyn Love says mechanical failure is to blame, an insulator on one of the utility’s lines broke. That’s a device used to help hold the line together. It’s unclear how it happened.

Love says power was restored to all customers around 12:45.