Power has been restored to National Grid customers in Amherst after a problem with transmission lines left nearly 20,000 people in the dark overnight.

The company said the problems started around 3 a.m. but by 5:30 a.m. nearly all service was up and running.

Crews were resetting traffic lights at the intersection of Sheridan and Alberta drives just before the morning commute picked up.

For some customers, this is the second time in a week they’ve lost power.