At least 18 people were killed in a quarry collapse in Somalia's capital Thursday, officials and witnesses said.

Nearly 200 workers were at the site in northern Mogadishu's Karan district digging for sand for use in building construction when the sudden collapse occurred.

"This was a tragedy. More than 16 dead bodies were discovered from under the collapsed quarry and still some others are missing," Karan district governor Ali Alasow said.

A worker who survived the accident, Mumin Abduweli, told AFP that he had seen 18 bodies.

"I have never witnessed such a tragedy, I was lucky to be outside of the cave when it collapsed," he said.

Another witness, Mohamed Yusuf, said those who died were digging deep inside a cave when it collapsed.

"Bulldozers have been used as well as people digging with their hands, but unfortunately only a few were lucky enough to come out alive," he added.

Since Islamist insurgents fled city trenches two years ago, bands of labourers have been rebuilding Mogadishu.

The quarry is often packed with casual workers hoping to make living from the building boom in Mogadishu, which was badly destroyed by decades of civil war.

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