Afghan attack kills US troops

An Afghan soldier turned his gun on American troops at a checkpoint in the country's east, killing two Americans and at least two fellow members of Afghanistan's army in a shooting that marked both the continuance of a disturbing trend of insider attacks and the 2,000th U.S. troop death in the long-running war. (AP)

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Gunfire and smoke is seen coming out of a building occupied by militants during a battle with Afghan-led forces, in Kabul, Afghanistan, Monday, April 16, 2012. The Afghan capital awoke Monday to a second day of explosions and heavy gunfire as Afghan-led forces worked to defeat insurgents holed up in the building in the heart of the city and another near parliament. (AP Photo/Musadeq Sadeq)
Gunfire and smoke is seen coming out of a building occupied by militants during a battle with Afghan-led forces, in Kabul, Afghanistan, Monday, April 16, 2012. The Afghan capital awoke Monday to a second day of explosions and heavy gunfire as Afghan-led forces worked to defeat insurgents holed up in the building in the heart of the city and another near parliament. (AP Photo/Musadeq Sadeq)