Bangladesh, Dec. 3 -- The United Nations headquarters in New York City was locked down for several hours Thursday after a man was seen pacing outside one of its main gates with a loaded shotgun, holding it under his chin at times, police said.

The man, who appeared to be in his 60s, was taken into custody without incident at around 1:40 p.m., about three hours after police said he was first spotted outside a U.N. security checkpoint on Manhattan's First Avenue. He was taken to a hospital for evaluation, NYPD Chief of Special Operations Harry Wedin said.

The gun was loaded with one shotgun shell, Wedin said. The man also had a bag with him and gave police documents, included medical papers, that he said he wanted delivered to the U.N., W...