Authorities in Boston city in the United States on Thursday began mass evacuations after at least 70 suspected gas explosions and fires erupted in the east coast towns of Lawrence, Andover and North Andover. At least six people were injured in these explosions, AFP reported.

All six were admitted to the Lawrence General Hospital, and two of them are in critical condition. “We continue to prepare for multiple casualties,” the hospital said.

Around 6.10 pm local time (3.40 am Indian Standard Time), the Massachusetts Police tweeted that it was too early to determine the cause of the explosions. They advised people who have a gas service from Columbia Gas to evacuate their homes immediately. “Gas lines are currently being depressurised by the company, and it will take some time,” the police said.

An hour later, they said that the power company had snapped electricity to Lawrence, Andover and North Andover towns. “Numerous evacuations of neighbourhoods where there are gas odours are underway,” the police said. “Far too early to speculate on cause. Joint investigation will be conducted when situation is stabilised.”

Massachusetts Governor Charlie Baker said he was “actively monitoring the situation”, and urged residents to obey local police officers.

Columbia Gas said in a statement that will be “upgrading natural gas lines in neighbourhoods across the state”.