JALALABAD, Afghanistan, June 7 (Xinhua) -- A couple were killed and their four children wounded when an unexploded mortar shell exploded in Afghanistan's eastern province of Nangarhar, the provincial government said in statement Thursday.

The incident happened on Wednesday afternoon in Chaparhar district in a family house and the injured children were aged between 10 and 14, the statement added.

The shell struck the house during an insider clash between two armed groups of Taliban in the past but the device did not explode then.

It was found by one of the family members in Dago area of the district, and blew up, when the person was trying to throw it away, the statement said.

Three of the wounded were rushed to the district township healthcare center, with one of them in critical condition shifted to provincial capital Jalalabad city, the statement said.

Landmines and anti-personnel mines kill or maim more than 50 people every month in the militancy-hit country, according to officials.

Unexploded ordnance and explosive remnants of war also frequently cause casualties among Afghans elsewhere in the country.?