One person was taken into custody early Friday after being found near the Pentagon with suspicious materials in his backpack, authorities said.

U.S. Park Police spokesman Sgt. David Schlosser said the man was in Arlington National Cemetery overnight, when it is closed, triggering an investigation. He said the man was initially uncooperative.

FBI Special Agt. Brenda Heck said the man was carrying a backpack that contained suspicious materials and a non-explosive material was found.

A law enforcement official speaking on the condition of anonymity said officials found what appeared to be a small quantity of ammonium nitrate, but the official, who was not authorized to release the information, said there was nothing that would have enabled an explosion. The official said tests were being done to determine the exact concentration.

Heck said in the course of the investigation, police were directed to a car, a red 2011 Nissan. No suspicious activity was said to be connected with the vehicle, she said, adding that the man was believed to be in his 20s. Heck said it is believed the man acted alone.

Pentagon police spokesman Chris Layman said the car was in bushes near the Pentagon's north parking lot.

In another incident earlier this week, a motorist found with a gun and what appeared to be a suspicious package near the Pentagon was taken into custody.

___

Associated Press writers Lolita Baldor, Jessica Gresko and Karen Mahabir contributed to this report.