Two policemen were killed when gunmen opened fire on their patrol vehicle.

当持枪歹徒对巡逻车开枪射击时，两名警察中弹身亡。

《柯林斯英汉双解大词典》

The trio were working with special forces carrying out a routine security patrol with Afghan forces when their vehicle was struck by a bomb blast and came under small arms fire.

遇袭时，这三人正与特种部队成员及阿安全部队执行例行的巡逻任务，他们乘坐的车辆遭爆炸袭击后受到轻武器火力攻击。

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The previous week unseen gunmen had opened fire on a joint patrol of American marines and Afghan soldiers.

上周，一拨行迹诡异的枪手攻击了参加联合巡逻的美军陆战队士兵和阿富汗士兵。

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They were in a fire-fight while on patrol in Helmand province in which an Afghan man, thought to be an off-duty policeman, also died.

BBC: Cpl Channing Day

His patrol came under fire from rifles and rocket-propelled grenades.

BBC: Prime Minister David Cameron in tribute to dead soldier

Exposed and with little available cover, the patrol was totally vulnerable to enemy rocket-propelled grenades and automatic weapons fire.

WHITEHOUSE: Medal of Honor for Staff Sergeant Robert J. Miller