NEW YORK (AP) — A man pulled a rifle from under his white lab coat and opened fire inside a Bronx hospital Friday, killing at least one person and wounding others before apparently taking his own life, authorities said.

The gunfire broke out at 2:50 p.m. inside the Bronx Lebanon Hospital, bringing police cars and firetrucks rushing to the scene and sending officers onto the roof with their guns drawn as people inside the building were told to hide.

Officers went floor by floor looking for the gunman and reported just before 4 p.m. that the shooter was dead inside the building. A law enforcement official told The Associated Press that the gunman apparently killed himself.

There was no immediate word on a motive, but the law enforcement official said the gunman may have been a former employee.

According to the law enforcement official, the shooter was wearing a lab coat and had the rifle concealed. The official was not authorized to discuss the still-unfolding investigation and spoke on condition of anonymity.

Police were still trying to identify how many people had been shot; emergency crews had been kept from going inside the hospital while the shooter was at large.

The 120-year-old hospital has nearly 1,000 beds and one of the busiest emergency rooms in New York City. It is about a mile and a half north of Yankee Stadium.