Manhunt under way for gunman in NYC subway shooting that injured at least 23

The attack unfolded as a Manhattan-bound subway train on the N line was pulling into an underground station in Brooklyn's Sunset Park neighborhood.

Police mounted an intense manhunt on Tuesday for a gunman who set off two smoke bombs and opened fire in a New York subway car, injuring more than 20 people in a morning rush-hour attack that prompted new calls to fight violence in the city's transit system.