"U.S. Sens. Elizabeth Warren and Ed Markey, D-Massachusetts, called on Congressional leaders Friday to immediately convene a hearing on gas explosions and fires that damaged homes and injured residents of Lawrence, Andover and North Andover on Thursday."

masslive.com/politics/index.ssf/2018/09/elizabeth_warren_ed_markey_see_1.html

Columbia Gas representative just got grilled by reporters; refuses to comment on possible cause of explosions due to NTSB involvement with investigation. Only they can make public statements on cause.