WASHINGTON (AP) -- Heavily armed insurgents attacked a British air base in southern Afghanistan Friday, killing two U.S. Marines and wounding several other troops, U.S. officials said.

Prince Harry, third in line to the British throne, is stationed at the base on a four-month combat tour. There was no immediate word on his whereabouts at the time of the attack.

U.S. officials said the attack at Camp Bastion in Afghanistan's Helmand province involved a range of insurgent weaponry, possibly including mortars, rockets or rocket-propelled grenades, as well as small arms fire.

Lt. Col. Stewart Upton, a spokesman at Camp Leatherneck, a U.S. Marine based adjacent to the air base, confirmed the attack and said two coalition service members had been killed but he did not specify their nationalities.

Upton said coalition forces were assessing the extent of the damage and would provide more details later.

Camp Bastion is a British air base and is used by the Marines at Leatherneck.

A number of aircraft at the base also were hit by insurgent fire, another U.S. official said.

Capt. Harry Wales, as the prince is known in the military, is serving a four-month combat deployment as a gunner on an Apache helicopter. Harry, who turns 28 on Saturday, is expected to start flying Apache missions this week. This is his second tour in Afghanistan.

It also was not clear Friday whether the attack was connected at all to the protests and violence across the Muslim world this week that has been linked to an anti-Islamic film. Afghanistan's southern region has been a hotbed of the insurgency and frequent attacks.