Three gunmen dressed in Afghan police uniforms have killed one US soldier and injured eight other US troops in southern Afghanistan, the International Security Assistance Force (ISAF) said in a statement issued early on Tuesday. "The International Security Assistance Force confirms that three individuals in Afghan police uniforms turned their weapons against coalition service members in southern Afghanistan yesterday, killing one ISAF service member," ISAF said. The assailants fled after the attack. ISAF spokesman Jamie Graybeal said that the three individuals are being sought. It is still unclear if the assailants were actually Afghan policemen or were just disguised as policemen. Other US officials, who spoke on condition of anonymity, said eight US troops were also wounded in the incident. Neither the ISAF spokesman nor the US officials gave any details on the location of the incident. However, a Kandahar police source said the incident occurred in Kandahar province and two US-led soldiers were killed in the attack. A total of 149 US troops have been killed in the war-torn Afghanistan so far this year, according to the website icasualties.org. A total of 418 US soldiers died in Afghanistan in 2011. The year 2010, however, remains the deadliest year for US military casualties with a death toll of 499. The increasing number of military casualties in Afghanistan has caused widespread anger in the US and other NATO member states, undermining public support for the Afghan war. The US-led war in Afghanistan began in 2001.