(Portland, OR)  --  Federal officers used tear gas on protesters in downtown Portland against last night after some of the protesters pulled down a fence surrounding the federal courthouse.  The incident happened just before midnight last night at the Mark O. Hatfield Federal Courthouse on Southwest 3rd Avenue.  The Oregonian reports last night's demonstrations had remained mostly peaceful up until that point.  The Portland Police Bureau has issued a statement saying they were not involved in last night's enforcements or crowd dispersals.