(Moorhead, MN) -- A two-alarm fire caused heavy damage to a duplex in North Moorhead this morning. Fire crews say this happened just before 7:30am off 17th Street North right near 4th Ave North. The fire began in the southwest corner of the duplex and crews had to fight through the walls to extinguish the blaze. No one was hurt but three people are said to be displaced. No cause on the fire at this time.