UPDATE: One dead, ten injured.
WCVB has the latest on multiple explosions this afternoon.
By 5:45 p.m., there were so many explosions that the Lawrence Fire Department knew of at least a dozen houses on fire they had not even been able to get to, Kilonum reports.
The Andover Fire Department reports that a total of 35 fires erupted just in that town - at one point, 18 were burning at the same time.
Shortly after 6 p.m. State Police urged anybody living or working in the 51,000 homes and businesses served by Columbia Gas to leave immediately.
At 7:10 p.m., State Police reported that National Grid - which provides electricity but not gas in the area - would be shutting off power.
Just today, Columbia Gas, which serves the Merrimack Valley, announced a major gas-main replacement project, including stretches in Lawrence, Andover and North Andover.
The MBTA is stopping Haverhill Line trains in Woburn due to the explosions in Andover. Exits off I-495 into Lawrence are shut; State Police are letting people in Lawrence and Andover get onto 495 to evacuate.
Shortly before 7 p.m., Boston Fire reported it was sending several companies of firefighters to the area. Boston Police will send several officers to help patrol the area overnight.