BILLINGS, Mont. (AP) — Billings Police are investigating a fourth casino robbery to occur in recent weeks, but can't say whether the crimes are connected.

The Billings Gazette reports (http://bit.ly/1cGiqjv) officers were called to Palms Grand Casino Sunday night when two masked men with handguns stole an undisclosed amount of money.

Sgt. Pat Curry says the investigation is ongoing.