More than 12 hours after crews began searching for a man buried by concrete and other debris in an underground explosion at a Bristol Pike gas station, an official said the operation has shifted from a rescue to a recovery effort. Federal authorities arrived on scene Wednesday morning. Fire Battalion Chief Rob Sponheimer on Wednesday says crews are focused on recovery because of high gas levels where the man was trapped following the blast at the Liberty Gas station near the Woodhaven Mall around 5 p.m. Tuesday. The explosion left another worker in critical condition with burns. Public Safety Director Fred Harran says the worker who was trapped was under heavy concrete that was blown apart in the blast.