LAWRENCE, Mass. — A series of gas explosions one official described as “Armageddon” left at least 10 people injured and ignited fires in at least 39 homes in three communities north of Boston on Thursday, forcing entire neighborhoods to evacuate as crews scrambled to fight the flames and turn off gas and electric lines to prevent further damage.Massachusetts State Police urged all residents with homes serviced by Columbia Gas in Lawrence, Andover and North Andover to evacuate, snarling traffic and causing widespread confusion as residents and local officials struggled to understand what was happening.“It looked like Armageddon, it really did,” Andover Fire Chief Michael Mansfield told reporters. “There were billows of smoke coming from Lawrence behind me. I could see pillars of smoke in front of me from the town of Andover.”Gov. Charlie Baker said state and local authorities are investigating but that it could take days or weeks before they turn up answers.“This is still very much an active scene,” he said. “There will be plenty of time later tonight, tomorrow morning and into the next day to do some of the work around determining exactly what happened and why.”Hours after the explosions, the utility’s parent company issued a brief statement saying its crews were still performing safety checks in the area.