This is really sad man. A 5-year-old boy died late Monday after being shot in the head by suspected gang members while in the backyard of a South Los Angeles home as he prepared for Halloween, police said. Aaron Shannon Jr. ran into the backyard to show off his Spider-Man costume Sunday to his uncle, grandfather and cousin when two men armed with handguns opened fire in the alley behind the home. At least one of the rounds struck Aaron in the back of his head; his uncle was hit in the leg and his grandfather on the wrist. "This is absolutely horrific. This is 2 p.m. on Halloween," said Los Angeles Police Deputy Chief Pat Gannon, who oversees South Los Angeles' policing. "This little boy was getting ready to go trick-or-treating. It is one of the most exciting days of the year for young children, and then they opened fire on this innocent family. "There is no reason for this shooting," he said. "It makes no sense. This family has no gang ties. The shooters Ã¢â‚¬Â¦ they are nothing but cowards." Late Monday, authorities said the shooting can be linked to the rivalry between the Kitchen Crips and Swan Blood gangs. Investigators believe the gunmen had mistaken the location for the one they had intended to fire on. William Shannon, Aaron's grandfather, said doctors at Harbor-UCLA Medical Center tried to save Aaron, but he died around 10 p.m. "These guys need to be taken off the streets," he said of the shooters, appealing to the public for help in capturing the two assailants. The shooting, he said, came without warning. "We were in the backyard and [Aaron] was in his Halloween costume.... He was very excited and was showing his speed and agility as Spider-Man. He was showing the costume's muscles like they were his, and I took a couple photos," Shannon said. Aaron, who attends elementary school in Compton, was going to a Halloween party in Inglewood, the grandfather said. Shannon said he saw two black males in their 20s walking in the alley behind the home in the Florence neighborhood. He said he nodded to acknowledge them. Shannon said he then heard a popping sound like small explosions or fireworks. "I saw one of the men move to position himself to get a clear shot off and he pointed a weapon and pulled the trigger," the grandfather said. "I turned around and I got shot in the left wrist and he continued to fire as we were running." When the gunfire stopped, Aaron was down. "My grandson was in a pool of blood in his Spider-Man costume. They shot him in the back of the head," Shannon said.