A journalist covering the clashes between Nigerian security forces and supporters of a Shia group in Abuja has been confirmed dead, amid reports the death toll has risen to at least eight people.

Members of the Islamic Movement of Nigeria (IMN) rallied on Monday in the capital demanding the release of their leader Ibrahim el-Zakzaky – in detention since 2015 – following reports of worsening health conditions of both he and his wife, who is also being held.

A senior police officer deployed to coordinate security operations during the protest was shot dead, police said.

IMN said they had retrieved six bodies of their members snot dead by during the clashes, but put the death toll higher. “I can confirm that 11 of our members were shot dead during yesterday’s protest,” Abdulhamid Bello, an IMN leader, told Al Jazeera on Tuesday. “We are still counting the death toll,” Bello Said.

Precious Owolabi, who worked for local broadcaster Channels Television, also succumbed to bullet wounds after he was shot while covering the protests. The 23-year-old was reportedly shot in the stomach. “The management and staff of Channels Television are greatly saddened by the untimely and unfortunate death of such a promising journalist,” the media organisation said in a statement.

Tributes have poured in for the slain journalist on social media, while The Nigeria Union of Journalists (NUJ) condemned his killing. “The death of Precious Owolabi signifies how brutish and short life has become in Nigeria and signposts the danger faced by journalists daily in carrying out the constitutional mandate of holding government and its officials accountable to Nigerians,” Emmanuel Ogbeche, NUJ chairman in Abuja, said in a statement.

Meanwhile, police said 54 Shia members who were arrested on Monday would soon be prosecuted. “The suspects are undergoing interrogation and will be arraigned in court as soon as possible,” a police statement read.

The Shia movement condemned the arrest of some of its members from hospital beds while receiving treatment for bullet wounds sustained during the bloody clash.