Suspect Adam Grennan didn't realize police officer Kamau Pritchard was standing behind him, in uniform, about to draw his weapon and place the man under arrest, The Boston Globe reported.

"He doesn't realize I'm behind him," said Pritchard, who was working security at the bank when the robbery attempt occurred. "He's focused on actually getting the money."

Pritchard was on break but was alerted to Grennan's suspicious behavior by the branch's assistant manager.

By the time he returned to the lobby, Grennan had allegedly passed the note to the teller, who handed over a stack of bills before saying, "He's trying to rob me," Pritchard said.