Updated

A buried bomb killed two children in eastern Afghanistan who triggered the explosive when they were playing outside near their village, officials said Monday.

Both of the children killed in the Sunday blast in Paktika province's Surobi district were about 12 years old, the governor's office said in a statement. Another child was seriously wounded, the statement said, without providing further details.

Last year was the deadliest on record for civilians in the Afghan war, with 3,021 killed, according to U.N. figures. Taliban-affiliated militants were responsible for the vast majority of those deaths.

Military casualties also continue to mount. On Monday, a NATO service member was killed in an insurgent attack in the south, the military alliance said in a statement.

The coalition did not provide further details. NATO forces usually wait for member nations to provide specifics on casualties.

The latest death makes 41 international service members killed in April and 132 so far this year — the majority of them American.