NEW YORK (Reuters) -Investment giant Blackstone Inc ( BX ) said on Tuesday that a senior executive was among the people killed when a gunman, carrying an assault rifle, walked into the lobby of a midtown Manhattan office building and opened fire on Monday.

"We are heartbroken to share that our colleague, Wesley LePatner, was among those who lost their lives in the tragic incident at 345 Park Avenue. Words cannot express the devastation we feel," the company said in a statement.

LePatner was a senior managing director at the firm and Global Head of Core+ Real Estate and the Chief Executive Officer of Blackstone Real Estate Income Trust (BREIT), the firm added.

The shooting occurred on Monday afternoon at 345 Park Avenue, the office building where Blackstone has its New York headquarters, and just as employees were getting ready to leave for the day.

Blackstone CEO Stephen Schwarzman and President Jon Gray wrote a note to all staff on Monday calling the day the "worst day in the firm's 40 year history," according to sources who saw the memo. The executives also said that Blackstone's New York office will be closed on Tuesday.

Later on Tuesday morning, Blackstone will hold a Zoom call, sources familiar with the matter told Reuters.