Four underwater unmanned vehicles went missing Sunday during training to conduct search, classify and map missions. The Navy, Coast Guard and local authorities were searching for the missing vehicles in the Thimble Shoals Channel between the Hampton Roads Bridge-Tunnel and the Chesapeake Bay Bridge-Tunnel, a Navy news release said. Communication was lost with four of the 13 unmanned vehicles Sunday about 1 p.m. while the vehicles were using bottom-mapping sonar to look for mine-like contacts in the water as part of the training. Search and recovery operations began immediately. Efforts continued Monday using small-craft, shore-based teams, air assets and marine...