Nigerian police have killed three more Shia Muslims as clashes erupt over the detention of a respected Shia cleric and deadly raids by the army on members of the community.

A spokesman for the Islamic Movement of Nigeria (IMN) said on Tuesday that police opened fire on people demonstrating in the northern city of Kaduna, killing three people and injuring several more.

Clashes were also reported in Kaduna’s Tudun Wada area, where people chanted slogans against the Nigerian army, condemning the December 12 attack on a religious gathering in the northern city of Zaria, located about 82 kilometers (51 miles) north of Kaduna. Local sources said hundreds of people were killed in Zaria.

The protesters were also demanding the release of revered Nigerian Shia cleric Ibrahim al-Zakzaky, who was arrested along with his wife during a raid by the army on his residence and the buildings connected to the Shia community in Zaria during the early hours of Sunday.

Reports said schools and businesses were closed in Tudun Wada as the number of people attending the protest increased.

The Nigerian army on Tuesday confirmed the arrest of Sheikh Zakzaky, saying he and his wife are safe and in protective custody in a secured facility.

An IMN spokesman said, however, that the deadly raids on Shias over the past days and detention of Zakzaky were pre-planned, accusing the government of deliberately targeting the members of Nigeria’s Shia community.

Human rights groups and activists have strongly denounced the Nigerian government for violating religious and social freedoms by attacking peaceful Shia gatherings.

The Nigerian army had also targeted Shias in August last year as people were holding a demonstration to condemn Israeli attacks on Palestinians.

Shias in Nigeria have also been targeted by the Takfiri militant group Boko Haram. More than 20 people were killed on November 27 in a Boko Haram bomb attack targeting Shia Muslims during an annual religious procession in the northern state of Kano.