The glittering skyscraper where hundreds work became the scene of New York City’s deadliest gun attack in 25 years when a man entered the lobby and started shooting.

The lobby of 345 Park Avenue will reopen for the first time since last Monday's mass shooting that left four innocent victims dead.

The office building, located at 345 Park Avenue, houses some of the country’s top financial firms, including Blackstone, and the National Football League. According to the company's website, Blackstone stands as the world’s largest alternative asset manager, managing over $1 trillion in assets under management.

A shooter killed five people and injured six at 345 Park Avenue before taking his own life, via the New York Post. At least one of those killed was a police officer. Per the report, authorities expect the number of victims to rise as the 44-story building is searched in the aftermath of the incident.

Employees at firms including Blackstone and KPMG hid and set up barricades during the gunman’s rampage.

NEW YORK (Reuters) -A spokesman for audit and advisory firm KPMG said in a statement the office at 345 Park Avenue will be closed on Tuesday, after a shooting in the building on Monday evening that left four dead, including a Blackstone executive.

The shooter who reportedly shot two persons outside 345 Park Avenue before fleeing into the building reportedly has died. Via ABC News, the shooter fled into the building and died on the 33rd floor, by suicide. Two individuals reportedly were shot outside the building.

An active shooter incident occurred in Midtown Manhattan, New York, officials said. Here's what to know about 345 Park Ave.

The New York City office building where a gunman fatally shot four people and himself reopened Monday, one week after the deadly rampage.Workers returned to 345 Park Ave., in Midtown Manhattan under the watchful eyes of NYPD officers and a surplus of additional security following the mass shooting.