KABUL, Afghanistan (CNN) -- An explosion that destroyed a building in downtown Kabul killed 9 people -- at least three of them Americans -- and wounded at least seven others, witnesses said. The blast occurred at 5:35 p.m. Sunday (1435 GMT) and appeared to have targeted the offices of DynCorp, a U.S.-based security company, and may have been caused by a remote-controlled bomb in a vehicle. Windows in nearby buildings were blown out. DynCorp has a police training facility in the Shar-e-Naw district of Kabul, where the explosion occurred, and has been providing security for President Hamid Karzai. Witnesses reported four Americans dead, but the U.S. Embassy in Kabul said that three Americans were killed and another was critically wounded. Three of the dead were Afghans and the other three were Nepalese Gurkhas who were working for DynCorp, witnesses said. "It's quite clear in my mind that they were targeted," said Nick Downie, an independent security expert working with non-governmental organizations. He was seated in his office when the blast erupted 50 meters away, blowing in his windows. "We went into a scene of absolute chaos and devastation," he said. A woman who answered the phone at the company's U.S. headquarters in Virginia said she had no comment. In a written statement, the U.S. Embassy said it was "shocked and saddened to learn that Americans, Afghans and other foreign nationals were killed" in the explosion, and that an investigation was under way. "This cowardly attack will not deter U.S. participation in the ongoing effort to help Afghanistan stand on its own feet," said Special Presidential Envoy and U.S. Ambassador Zalmay Khalilzad in the statement. "Rebuilding Afghanistan's security institutions is a vital step toward the creation of a secure, peaceful country. The United States is committed to Afghanistan's success - the training of police and the army will continue to go forward." Al-Jazeera reported that Taliban officials told them over in telephone messages that their group was behind the attack. "We received two phone calls from two Taliban spokespersons -- Mulla Janan and Mulla Hakim -- who claimed the movement's responsibility for the blast and regretted the injuries inflicted on some Afghan people who were accidentally passing by the area," said Al-Jazeera's Kabul correspondent, Mazin Aman Allah. Local radio said a Pakistan-based militant group claimed responsibility for the blast, calling it an attempt to undermine the nation's first post-Taliban presidential elections, scheduled to take place Oct. 9. Troops were ordered inside their bunkers, Lt. Commander Ken Mackillop said. Also, an Apache helicopter with the International Security Forces crashed six miles south of Bagram Air Base, Mackillop said. Both crew members were unhurt. The cause was being investigated.

__________________

The difference between 'involvement' and 'commitment' is like an eggs-and-ham breakfast : the chicken was 'involved' - the pig was 'committed'