A 17-year-old boy from Chicago was killed in an all-terrain vehicle crash in Concord on Thursday.At about 5 p.m., the boy and a group of friends had been taking turns riding an ATV behind a home where they were visiting. The boy was taking his turn on the ATV when one of his friends heard a loud crash. The group found the boy unresponsive. The friends quickly began CPR and called 911. Concord firefighters transported the boy to Concord Hospital, where he was pronounced deceased.The on-scene investigation showed the boy lost control of the ATV and struck a tree at a high rate of speed. He was riding on private property, where he had permission to be, but was not wearing a helmet.The accident is still under investigation, but based on the preliminary investigation, it appears that speed and inexperience are the primary contributing factors in the collision, according to New Hampshire Fish and Game.People under the age of 18 are required under state law to wear a helmet and eye protection while riding off-highway recreational vehicles, Fish and Game said.