A New Jersey man walked into a federal building near the SoHo neighborhood of Manhattan on Friday afternoon and fatally shot a security guard before killing himself, the authorities said.

Law enforcement officials said the victim, Idrissa Camara, 53, was a private security guard who worked inside the building at 201 Varick Street, The New York Times reported on Saturday.

“The perp walks in the door, goes into the security line, pulls out a gun” and shoots the guard, an official said.

A police official identified the gunman as Kevin Downing, 68, a military veteran from Fort Lee.

The authorities said late Friday that they had learned that Downing had claimed publicly, including on the Internet, that he was a onetime employee of the federal Bureau of Labor Statistics who had been fired more than a decade ago after criticizing the agency’s spending. He did not have a criminal record.

The bureau has an office in the federal building, though the authorities said it was unclear if Downing ever worked there. “It’s going to take a while to figure out the motive,” one law enforcement official said.

Speaking to reporters outside the federal building on Friday, James P. O’Neill, the chief of department of the New York Police Department, said the gunman opened fire at 5:05 p.m. and then walked farther into the building.

When he reached the elevators, he “encountered another employee” and then fatally shot himself in the head. The second employee was not a guard, Chief O’Neill said.

“There is no indication of a connection to terrorism,” Chief O’Neill said. The authorities said it was not clear if there were any ties between the gunman and the security guard.