A mortar shell explosion in Somalia’s Lower Shabelle region has killed more than 20 mostly children and young people and injured more than 50, according to media reports.

Most of the victims who were killed on Friday were aged between 10 and 15 years, according to news reports, which blamed the blast on an unexploded mortar shell that was struck and detonated near an area where the children and young people were playing.

The explosion “caused by unexploded mortar shells” occurred near the town of Qoryoley, approximately 120km (75 miles) south of the capital, Mogadishu, said Abdi Ahmed Ali, deputy district commissioner of Qoryoley.

“They were playing with a mortar shell … It exploded on them. Twenty of them died and others are injured,” Ali said.

“We request the government and aid agencies to clear mines and shells from the area,” he said.

Residents said that Somalia’s warring factions had left the shell behind at some stage.

Another report said the children had found an intact explosive device on a football field and were playing with it when it exploded. Recent rainfall had uncovered the explosive device, according to reports.