A man was shot by police after an incident involving a gun at the end of a Christmas choral concert on the steps of a Manhattan cathedral in New York.

It is unclear if the gunman was killed or if any others were injured.

The shooting happened just before 4pm local time at the Cathedral Church of Saint John the Divine, mother church of the Episcopal Diocese of New York and seat of its bishop.

The 45-minute concert had just concluded and people were starting to walk away when a series of shots was heard, sending people running down the street screaming.

Officers who had been on hand to provide security for the event quickly moved in and shot the gunman, who police believe was armed with a rifle.

The man was taken to a hospital in critical condition.

Police Commissioner Dermot Shea and Chief of Department Terence Monahan were headed to the scene.