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Three US soldiers among at least 14 killed by Afghan suicide bomber

A suicide bomber detonated a device in Afghanistan on Monday, killing three U.S. soldiers, one interpreter and four members of the Afghan National Police, a military official told NBC News.

The U.S. soldiers and Afghan police were on a dismounted partner patrol near the center of the Khost region in eastern Afghanistan. The attacker approached and detonated as they were preparing to get back in their vehicles.

Six civilians also died in the attack, Reuters reported. 

Despite reports that the bomber was riding a motorcycle, the official said there was no evidence of that. The official added that the dead interpreter is thought to be Afghan.

More Afghanistan coverage from NBC News

On Saturday night, an Afghan soldier approached Americans, killing a soldier and a contractor; with that, the number of soldiers killed in Afghanistan is around 2,100 in the United States' 11-year-war in the country. Insider attacks have become increasingly common – and no one seems to have a good answer about how to stop them. NBC's Lester Holt and Richard Engel report from Kabul.

A witness told Reuters a suicide bomber was wearing a police uniform.

The bombing followed the killing of two Americans on Sunday in an exchange of fire with Afghan forces.

Insider attacks by members of the Afghan security forces against NATO allies have resulted in at least 52 deaths this year among foreign forces and this month prompted a tightening of rules for joint patrols between coalition and Afghan forces. 

NBC's Richard Engel examines America's progress after fighting for more than a decade in Afghanistan. Is there any evidence that the American plan to hand over a credible, stable Afghan government will work?

Reuters contributed to this report.

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