(Portland, OR) -- The Portland Police Bureau says officers responded to 13 shootings in 28 hours over the weekend. One person was killed and three people were injured. Five shots fired calls came in during one three hour period, and the bureau's resources were so strained that a sergeant was the only person gathering evidence at one incident while citizens were used to control traffic at the scene of another shooting. Investigators believe some of the shootings were related. At least 151 casings were recovered from all of the crime scenes.