PORTLAND — Northwest Natural Gas wants customers to be alert for a new scam that’s circulating.

Scammers call customers claiming to be from NW Natural. The scammers tell the customer they have a past due payment that needs to be paid immediately with cash to avoid having gas shut off. The caller directs the customer to go to a Western Union and then call back for details on where to wire the cash payment. Over the past three weeks, seven different NW Natural customers were contacted.