SWAMPSCOTT – An incident involving an improvised explosive device that detonated and injured a 13-year-old remains under investigation by several agencies.Swampscott Police Detective Ted Delano said the incident is still under investigation by the Swampscott Police, the State Police and the Department of Social Services.Late Thursday afternoon, police received a 911 call reporting an explosion with injuries at the Bernard Surette residence, 92 Melvin Ave.The juvenile, who neighbors identified as Joel Surette, allegedly created the improvised explosive device in his home and the subsequent blast reportedly blew off two of his fingertips.”It is still under investigation,” Delano said. “It appears he took a bunch of powder from caps used in cap guns and powder from snap poppers you toss on the ground. He combined the powder to make an improvised explosive device.”According to police, the juvenile removed the powder and put it into a cardboard container, which he secured with tape.Delano, who said there was no substantial damage to the home, said police spent almost two hours collecting evidence in the home and from trashcans outside the residence. But because the incident is still under investigation he declined to comment on whether weapons or other explosives were found at the scene. Delano pointed out as a result of the investigation it was found the pop snappers, small devices that explode when thrown onto a hard surface, are illegal.”At this time the 13-year-old juvenile appears to be the only person involved,” he said. “At this time we can’t comment on whether the parents or other adults were present when the explosion occurred. The juvenile is still at Mass. General Hospital and the Department of Social Services is investigating because of the nature of the incident.”Delano said an explosion in the same area of town set off car alarms last Saturday but when police arrived they did not find evidence of an explosion and could not locate the person responsible.This is not the first time an incident like this has occurred in town. In March 2007, four juveniles went online and downloaded instructions on how to build a bomb using common household chemicals. One of the juveniles was injured and suffered severe burns to his eyes when the mixture exploded.