(Portland, OR)  --  Multnomah County Sheriff's officials are warning residents about a phone scam that's struck several residents.  Officials say the scammers are calling people and claiming to be either Captain Mitchell or Lieutenant Brown.  The scammers then tell the victim the have either a warrant or unpaid fines that need to be paid right away.  The Sheriff's Office reminds residents that they never address those matters over the phone, and that if they receive a call like this, they should hang up and call police to file a report.