New York, March 29 -- A Bangladeshi teenager undergoing a "mental crisis" has been shot dead by city police after he lunged at them with a pair of scissors and his mother intervened in their attempts to subdue him, according to police.The incident started with a phone call to an emergency police line that Win Rozario, 19, had himself made on Wednesday afternoon, New York Police Patrol Chief John Chell said at a news conference.

City police were already on edge after a gunman killed one of them on Monday.

Chell said that when police arrived at the teen's home, Rozario was in a "mental crisis" and the situation was "quite hectic, chaotic and dangerous".

When he charged at them with scissors, police fired a Taser to subdue him but his "mo...