(Portland, OR)  --  An investigation is ongoing into a fight involving two groups of people near Waterfront Park in downtown Portland.  Police say people used bear spray, air soft guns, and paintball guns against each other during the fight Sunday night.  Police say they were working a robbery and a homicide and didn't have enough officers to safely respond to the fight.  No arrests were made.  Anyone who was the victim of a crime should report it to Portland Police.