KABUL (Reuters) - Three American and two Latvian soldiers were killed in an attack by insurgents in eastern Afghanistan on Friday, US forces and Latvias Defence Ministry said. US military spokeswoman Captain Elizabeth Mathias said insurgents attacked an outpost in the eastern sector with small arms fire and rocket-propelled grenades and struck an ammunition store, causing an explosion. Latvias Defence Ministry said the western soldiers were killed with three Afghan soldiers in the attack by Taliban fighters or other insurgents in eastern Afghanistans Kumar region. The Latvian soldiers were on a mission to train the Afghan National Army, said Normunds Stafeckis, a spokesman for Latvias Defence Ministry, adding several other soldiers were injured in the attack. International and Afghan forces returned fire and called for support from the air, said US Mathias, but gave no further details of the location of the incident. The eastern sector includes 14 provinces, some of which have seen major fighting. Latvia has around 160 soldiers in the NATO-led force in Afghanistan.