KABUL, AFGHANISTAN - An attacker wearing an Afghan Army uniform killed an international service member in southern Afghanistan on Sunday, NATO said. Afghan officials said international forces returned fire, killing one member of the Afghan Army.

The international service member who died was British, and the attack took place inside a small district camp in Helmand Province used by both Afghan and British soldiers, said Sayed Malook, a senior Afghan Army commander in Helmand.

Two Afghan officials, who spoke anonymously, said it was unclear whether the Afghan soldier who had been killed had carried out the original shooting.

As a result, the British security forces and Afghan police sealed off the camp compound, disarmed the Afghan soldiers inside the camp and were checking their weapons to discover who had fired shots. Helicopters were hovering over the compound, in Nad Ali district of Helmand, checking for anyone who might have fled the camp.

Helmand Province, where the attack took place, is where most of the 9,500 British forces in Afghanistan are concentrated.

In three other episodes, 10 Afghan civilians died in separate explosions on Saturday and Sunday involving roadside bombs. In Khost Province, a family was returning from the hospital late Saturday with their newborn baby when their car hit a roadside bomb, killing all six in the car.