Calvin Spencer, 33, has been arrested in connection with a stabbing in Boston's Downtown Crossing on Wednesday morning. The victim, who sustained multiple stab wounds to the back and arm, is expected to survive. Spencer was captured on transit security footage discarding a knife and hat on the Downtown Crossing platform and fleeing shirtless from Andrew Station. He was arrested shortly thereafter on unrelated warrants, including failure to register as a sex offender. The incident has heightened safety concerns in the area, prompting City Councilor Ed Flynn to recommend canceling scheduled events in Boston Common. Spencer is set to be arraigned on Thursday in Boston Municipal Court on charges including assault and battery by means of a dangerous weapon.