RAPID CITY, S.D. (AP) — Black Hills Energy is investigating what caused two power poles to collapse in Rapid City, knocking out power and causing a small oil spill.

Officials say no one was hurt when the poles crashed near the Time Inn Motel and Time Out Lounge Wednesday afternoon. Police say it’s not known what caused the poles to topple. One landed on a Dumpster and the other hit the roof of one of the motel buildings.

About 300 utility customers lost power. The Rapid City Journal says a transformer at the top of one of the poles began leaking oil after hitting the trash bin.