Power was expected to be restored Thursday morning after a lengthy outage caused Wednesday when a Western Disposal truck's boom hit a power line in the 2300 block of Canyon Boulevard in Boulder.

The outage, which affected 25 to 30 residential and business customers, occurred

Workers prepare one of two broken power poles to be taken down in Boulder on Wednesday afternoon. (Paul Aiken/Camera)
about 12:15 p.m. The truck knocked down two power poles, causing two transformers to fail and creating an outage that wasn't expected to be fixed until 6 a.m. Thursday, according to Boulder police spokeswoman Sarah Huntley.

The outage at one point affected about 2,400 Xcel Energy customers and darkened several Boulder intersections. A portable generator arrived about 3:40 p.m. Wednesday to power the signals at the busy intersection of Folsom Street and Canyon, Huntley said.

At the time of the accident, the truck was delivering a Dumpster to two office buildings at 23rd Street and Canyon Boulevard. It drove too close to the power lines with its crane arm still partially raised, according to witnesses, and the arm tangled in the power lines, snapping two poles.

One of the poles was partially resting on the roof of an office building at 2355 Canyon Blvd. when police and firefighters arrived on the scene. Boulder police evacuated the office buildings at 2355 and 2305 Canyon Blvd. as a precaution.

"We're worried about the line snapping and the pole falling down and hurting someone," said Dave Gelderloos, spokesman for the Boulder Fire Department.

Gelderloos said early reports of an explosion likely resulted from a combination of sounds made when an electrical current tripped the transformer on one of the poles and a flash generated by live power lines crossing one another.

Gary Baraff, who was inside the 2305 Canyon building when the power poles were downed, said he heard the transformer hit the building before it was evacuated.

"It was pretty urgent," he said. "The fire guy thought the building could become electrified."

The Western Disposal truck driver, who was not injured, declined to comment.