On May 5 at around 9:30 a.m., several teams of Pima County, Ariz., police officers from at least four different police agencies armed with SWAT gear and an armored personnel carrier raided at least four homes as part of what at the time was described as an investigation into alleged marijuana trafficking. One of those homes belonged to 26-year-old Jose Guerena and his wife, Vanessa Guerena. The couple's 4-year-old son was also in the house at the time. Their 6-year-old son was at school.

As the SWAT team forced its way into his home, Guerena, a former Marine who served two tours of duty in , armed himself with his AR-15 rifle and told his wife and son to hide in a closet. As the officers entered, Guerena confronted them from the far end of a long, dark hallway. The police opened fire, releasing more than 70 rounds in about 7 seconds, at least 60 of which struck Guerena. He was pronounced dead a little over an hour later.