More than 20 people were killed on Tuesday when heavily-armed “extremist Christians” attacked mourners at the funeral of a Muslim elder and destroyed property belonging to Muslim residents, according to a local Islamic group.

Desalegn Tassew, head of the Amhara region’s peace and security bureau, said 373 suspects had been arrested “in relation to the disturbance that happened in Gondar”, according to a statement cited by the official Amhara Media Corporation.

He also announced a ban on firearms and other weapons until all suspects were arrested.

“We are making legally accountable members of the security forces and leaders who did not assume their responsibility,” he added, without elaborating.

The cemetery where the attack occurred neighbours a mosque and church and has been the subject of an ongoing dispute between Muslims and Orthodox Christians, who are the dominant group in Ethiopia.

Amhara’s regional government said the violence erupted as people clashed over using stones from the area for burial purposes, fighting over whether the materials were being taken from the cemetery or church compound.

In Ethiopia’s capital Addis Ababa on Friday, Muslims staged a demonstration over the Gondar violence as they gathered for a mass iftar, the traditional sunset meal breaking the fast during the holy month of Ramadan.

“Justice for Amhara victims in Gondar,” they chanted. “We need fair justice.”