(Portland, OR)  --  A man is facing multiple charges after allegedly threatening a food cart worker with a stolen gun in downtown Portland.  Police say Dominique Mann walked up to the food cart on Southwest 2nd Avenue and Oak Street Sunday night and used a gun to threaten a worker there.  He then allegedly returned to the food cart half an hour later and fired a round into the air.  Responding officers fired foam-tipped projectiles at Mann, prompting him to surrender.