State police are asking for assistance in locating a missing teen. The 17-year old was last seen leaving his residence on March 27 around 11:30 a.m., police said. The teen, Gavin J. Simmons, 17, was allegedly wearing a black sweatshirt, light colored blue jeans and silver Nike sneakers when he was last seen. Simmons is believed to have been headed to Gouverneur or Watertown, troopers said. Police are asking anyone with information to contact state police at 518-873-2750.