 The Maryland Fire Marshal's Office is investigating the cause of an overnight fire at Captain Zach's Crab Shack on Route 213 south of Elkton. Firefighters from Singerley in Newark responded to the fire just before 4 a.m. at the facility, which is located behind Sarge's Market. Fire officials say the market was not damaged, but crews remained on scene for several hours while a 500-pound propane tank was allowed to burn off.