A gunman in a bulletproof vest reportedly opened fire inside a Manhattan skyscraper on Monday, injuring at least two people.

The shooter, armed with an assault rifle, allegedly injured a police officer and a civilian, reports The New York Post, citing law enforcement sources.

The New York Police Department warned of “police activity” at the Midtown office tower, which is home to the headquarters of the NFL and asset manager Blackstone, and urged the public to stay away.

Large numbers of police were photographed outside the building at 345 Park Avenue, including SWAT units.

The tower is currently on lockdown, ABC7 reports.

This is a breaking news story and will be updated with new information.