Although federal investigators are unsure of what caused Sunday’s deadly explosion at a powerplant under construction in central Connecticut, local officials are saying the accident occurred during gas line purging, or blow-down operations, in preparation for the facility’s scheduled opening this summer. Photo: AP Photo/Seth Wenig Michael Rosario, business representative for the Plumbers, Pipefitters, & HVAC Local 777, hugs a friend after telling reporters about losing three friends in the explosion at the Kleen Energy Systems power plant on Sunday in Middletown, Conn. The accident occurred just three days after the U.S. Chemical Safety Board approved recommendations on gas purging,

Though federal investigators are unsure of what caused Sunday’s deadly explosion at a power plant under construction in central Connecticut, local officials are saying the accident occurred during blowdown operations in preparation for the facility’s scheduled opening this summer. AP Photo Related Links: Lawsuit Alleges Safety Protocols Ignored in Kleen Energy Blast Although reports are unconfirmed that authorities are investigating the possibility that a welder’s torch may have created the spark that caused the blast, a spokesman for the project owner, Kleen Energy Systems, said that police were still treating the site as a crime scene. The accident occurred just