A Californian man, who harboured ill feelings towards the US administration and the country's armed forces, on Friday coolly walked up to the Pentagon's screening area and shot two police officers before being fatally wounded, leading to security lockdown of the US military headquarters for hours.
The man suddenly opened fire at the metro station entrance of the Pentagon at 6:40 pm local time Thursday (0510 IST Friday), forcing the security officers to return fire with automatic weapons, which grievously wounded him.
The gunman later identified as 36-year-old John Patrick Bedell from California succumbed to his bullet wounds in hospital.
The man -- with "no real emotion in his face" -- approached the officers outside the Pentagon Metro station, Pentagon Police Chief Richard S Keevill was quoted as saying in the US media.
"As the officers started to ask him for his pass to get into the Pentagon, he drew a weapon from his pocket and started shooting from a few feet away," Keevill told media persons.
The two officers of the Pentagon Force Protection Agency retaliated with their semi-automatic weapons and the gunman was critically wounded, Keevill said. "He did not say a word."
In a statement, Pentagon said the entrances were locked briefly, but all were reopened with the exception of the Pentagon Metro entrance.
Officials said they found Bedell had no terrorist connections but had not ruled it out till investigations were complete.
Bedell's death was confirmed hours after the evening assault as authorities searched for a motive behind the brazen attack.
Two Pentagon protection police officers, who were grazed by bullets, were treated in a hospital and declared out of danger.
Later, police sources said a search of Bedell's premises led investigative authorities to find Internet postings under his name where he exhibited ill-feelings towards the American armed forces and questioned the circumstances behind the 9/11 terrorists attacks.
The assault on Pentagon came months after a deadly attack on the Army's Fort Hood complex in Texas by a Muslim army officer with radical Islamic leanings.
Police were also on the lookout for a second man, suspecting he may have accompanied the shooter. The subway station is immediately adjacent to the Pentagon building and since 9/11 attacks, security has been redesigned that visitors can no longer disembark directly into the building and have to take an escalator to reach the surface from the underground station.
They also have to pass through numerous security checks and routes.
As the attack unfolded at the subway entrance to the US military headquarters, all entrances to Pentagon were secured and a security lockdown ordered, which lasted for hours.
The subway station remained closed for the day.