Thursday evening's shootout between Pentagon police officers and a gunman apparently motivated by anti-government sentiment was the latest in a spate of attacks on federal employees and facilities and serves as a stark reminder that public servants too often find themselves unexpectedly in harm's way. The following timeline reviews major attacks during the past two decades.
Feb. 18, 2010. A small jet is flown into a building housing a federal tax office in Austin, Texas, injuring 13 and killing two. The pilot, Joseph Andrew Stack, was angry with the Internal Revenue Service.
Nov. 5, 2009. An Army psychiatrist goes on a rampage at Fort Hood, Texas, killing 13 people and wounding dozens. The alleged gunman, Maj. Nidal Malik Hasan, was a Muslim who had been in contact with a radical Imam and was about to be deployed overseas.
June 1, 2009. A gunman opens fire on a U.S. military recruiting office in Little Rock, Ark., killing one soldier and wounding another. The suspect, a Muslim convert, opposed the wars in Iraq and Afghanistan, but was not affiliated with a larger terrorist network.
Sep. 12, 2006. Four Islamic militants armed with guns, grenades and a car bomb attack the U.S. Embassy in Damascus, killing one and injuring 14. The attack came at a time of heightened anti-American sentiment because of U.S. support for Israeli military action in Lebanon.
Sep. 18, 2001. Envelopes containing anthrax and notes with radical Islamist rhetoric are sent to news organizations and two senators. Five people die and at least 22 people -- including postal workers -- are infected. The FBI said Bruce Ivins, an Army biodefense expert who committed suicide in 2008, orchestrated the attacks himself.
Sep. 11, 2001. Hijackers linked to al Qaeda crash a commercial jet into the west side of the Pentagon, less than an hour after the World Trade Center came under attack. Passengers seize control of Flight 93 from hijackers and crash the plane, thought to have been headed for the Capitol or White House, into a field in Shanksville, Pa. 189 die in the Pentagon; 2,751 die in New York, and 40 die in Pennsylvania.
Oct. 12, 2000. An al Qaeda suicide attack damages the Navy destroyer USS Cole in the port of Aden, Yemen, killing 17 sailors and injuring 39.
Aug. 7, 1998. Trucks loaded with explosives go off almost simultaneously outside U.S. embassies in Dar es Salaam, Tanzania, and Nairobi, Kenya, killing 233. A group linked to Egyptian Islamic Jihad took credit for the bombings, making Osama bin Laden and Ayman al-Zawahiri household names.
July 24, 1998. A paranoid schizophrenic enters the Capitol Building and opens fire, killing two police officers.
April 19, 1995. A homemade bomb destroys Oklahoma City's Alfred P. Murrah Federal Building, injuring more than 800 and killing 168. Army veterans Timothy McVeigh and Terry Nichols were behind the attack, which caused $652 million worth of damage. They claimed they acted to protect the Constitution.
Oct. 29, 1994. A gunman fires a semiautomatic rifle from a fence outside at the White House's north lawn at a group of men, thinking President Clinton is among them. (Clinton was reportedly in the family residence watching a football game.) Tourists subdue Francisco Martin Duran and no one is injured in the attack.
Sept. 12, 1994. In an attempt to assassinate President Clinton, Frank Eugene Corder, an alcoholic and drug abuser, flies a stolen plane from Aldino Airport in Maryland into the White House lawn. He dies in the attack.
Feb. 26, 1993. A car bomb goes off below the North Tower of the World Trade Center in New York, where some federal agency offices are located. The al Qaeda attack fails to bring down the towers as originally planned, but kills six and injures more than 1,000.
Jan. 25, 1993. A gunman fires on cars waiting near the entrance of the CIA's headquarters in Langley, Va., killing three agency employees and wounding two more. The shooter, Mir Aimal Kasi, was angry with U.S. policy in the Middle East.