WASHINGTON, Aug 23 (Reuters) - One member of the Afghan forces was killed and several were wounded in an exchange of gunfire outside Kabul airport on Monday, but no U.S. personnel were hurt, the U.S. military said. "The incident appeared to begin when an unknown hostile actor fired upon Afghan security forces involved in monitoring access to the gate. The Afghans returned fire, and in keeping with their right of self-defense, so too did U.S. and coalition troops," the statement said. On Thursday, the U.S. military used three military helicopters to take 169 Americans to the airport in Kabul from a building 200 meters (656 feet) away. On Monday, Pentagon spokesman John Kirby told a news briefing that U.S. troops based at Kabul airport flew a helicopter outside the airport perimeter a second time to collect Americans for evacuation flights. He said U.S. troops had used other means to collect Americans outside the airport but gave no details. Army Major General William Taylor, with the U.S. military"s Joint Staff, told the briefing about 5,800 U.S. troops were assisting evacuation efforts at Kabul airport. Kirby said several thousand Americans had been evacuated since Aug. 14 but declined to give details. He said the aim remained to finish the withdrawal by the end of August. With thousands of desperate Afghans and foreigners crowding into Kabul"s airport in the hope of fleeing Afghanistan"s new Taliban rulers, pressure has grown on U.S. President Joe Biden to extend his Aug. 31 evacuation deadline. read more "There"s a lot of people, and they are desperate," Kirby said. "We are trying to do the best we can to get them out of harm"s way as fast as possible."