The lights were coming on for Pocatello after an outage knocked out power for as many as 13,000 Idaho Power customers.
Pocatello police said a downed line not belonging to Idaho Power caused a small brush fire in the Rocky Point area, which tripped a breaker that around 4 p.m. Wednesday.
An Idaho Power spokeswoman said the outage can be traced to a transformer in the substation there. She said there was something wrong with the transmission line that distributes power to two major areas of Pocatello.
Idaho Power said that because the transmission lines were at full capacity with air conditioning and irrigation demand, it was taking longer to bring power on as a result, and that power was being restored incrementally on Wednesday night.
Police said the traffic lights were out at most intersections and cautioned drivers to treat them as four-way stops or use the side streets. The police department was also worried about people staying cool, as air conditioners and AC-powered fans were not working.