More than 40,000 Xcel Energy customers in Aurora and parts of Denver were without power for nearly two hours Thursday afternoon.

The power outage affected a large area from Quebec Street on the west, to Picadilly Road on the east, and from East 40th Avenue on the north to East Mississippi Avenue on the south, Tom Henley, Xcel spokesman, said. Power was restored about 3:30 p.m.

Xcel crews traced the source of the power outage to circuit feeders within a substation that malfunctioned, Henley said. A fire at a substation at East Colfax Avenue and Interstate 225 knocked out a few circuit feeders, Henley said. However, other circuit feeders that should have continued to operate and produce power for customers also malfunctioned.

Engineers and crews were trying to determine what caused the disruption to power.

An engineer was able to repair the problems and restore power.