New York Shooting UPDATES: Four dead including cop as gunman opens fire

At least four people - including one police officer - have been shot dead after a gunman opened fire in Midtown Manhattan on Monday evening.

Scores of people have been evacuated from homes and businesses following the shootings, most of which happened in a skyscraper housing several big businesses including the NFL, Deutsche Bank and the Blackstone Group.

People across the neighbourhood - which is now on complete lockdown - have been warned to be vigilant and "stay safe" amid the threat, meanwhile the New York City Police Department has told local media the investigation is moving at pace.

The off-duty police officer that was shot, is understood to have been working in his second job in security when he was shot in the back by the lone gunman. He has since tragically died in hospital while undergoing emergency surgery for his injuries.

A further civilian is also understood to be in a critical condition, while the extent of the injuries of other victims remains unknown.

The gunman himself, believed to be a 27 year old from Las Vegas was also confirmed dead at the scene after suffering from what are believed to be self-inflicted injuries.

An investigation is now underway to identify the motive behind the callous and tragic attack.

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