Three people were killed and three others injured in shootings over the weekend at homeless encampments in Minneapolis. No arrests have been made in the shootings at separate encampments a few miles from the city’s downtown, USA Today reports. In the first shooting, around 4:45am on Saturday, one man was killed and two others injured. In the second shooting, around 2:20pm on Sunday, two men were killed in an encampment along railroad tracks and a woman was hospitalized with life-threatening injuries. Police say the motive is unknown and it’s possible that the two shootings are linked.

“The cold-blooded killing of three people inside the tent of an encampment is outrageous,” Minneapolis Chief Brian O’Hara said in a statement Sunday. “All human life matters and encampments are not safe.” Minneapolis Mayor Jacob Frey said it was an “incredibly tragic and sad situation,” noting that shootings have surged in encampments while violent crime has dropped in other parts of the city, Minneapolis Public Radio reports. The mayor said the problem isn’t about a lack of shelter. “It’s about fentanyl,” he said. “It is about a drug that takes a hold of your body and your mind like nothing that we’ve ever seen before.” (More Minneapolis stories.)