FARMERSVILLE, Texas—Two people were killed and three injured in a natural gas pipeline explosion in Texas, officials said. The deadly blast happened around 4 p.m. Monday at an Atmos Energy facility in Collin County near Farmersville, about 35 miles northeast of Dallas. Collin County Sheriff Jim Skinner said the explosion appeared to be an accident but he invited the FBI to assist in the investigation. It was not immediately known what caused the blast. Those involved in the explosion were contractors for Atmos Energy, and the Collin County Sheriff’s Office said Monday night the contractors were employees of Bobcat Contracting and Fesco Petroleum Engineering. Two of the injured were taken to a hospital. The workers were servicing a gas line when the explosion happened, Farmersville police Chief Mike Sullivan told WFAA-TV. The Princeton and Farmersville fire departments, Collin County EMS and multiple other local law enforcement agencies responded to the …