This story has been updated.
Update 5:05 p.m., Tuesday, Jan. 8
The robbery has been confirmed by Arlington Police Capt. Richard Flynn. He said the suspect entered the bank at about 3:45 p.m. and left with an undetermined amount of cash. Police were still working the scene at about 5 p.m., according to Flynn. He said more details, including a photo of the suspect, who was heavily covered, would be available Wednesday morning.
The East Cambridge Savings Bank at 105 Broadway in East Arlington was robbed at about 3:50 p.m. Tuesday, according to @alertnewengland on Twitter.
The suspect claimed to have automatic weapon and fled toward Somerville, according to the report. He was wearing a black jacket and jeans.