BILLINGS, Mont. (AP) — Crews are trying to remove a barge that partially sank in the Yellowstone River in Montana.

Work continued Friday after the barge went down during a dredging operation near a refinery in Lockwood. ExxonMobil refinery spokesman Dan Carter says how the barge sank isn't yet known.

The Billings Gazette reports floating booms were set up around the barge as a precaution.

Montana Disaster and Emergency Services recovery supervisor Tim Thennis says no oil or chemicals spilled.

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Information from: The Billings Gazette, http://www.billingsgazette.com