At least six people were killed as members of the Islamic Movement in Nigeria (IMN) clashed with Nigerian police in the capital Abuja on Monday over the continued detention of their leader Sheik Ibrahim Zakzaky.
Other media reported that at least eight people were killed.
Ms Precious Owolabi, a 23-year-old journalist, and senior police officer Usman Umar are among those killed in the protests.
Ms Owolabi, a trainee journalist, was hit by a stray bullet and died late Monday while receiving treatment, BBC reported.
Police spokesman Frank Mba said two other officers were seriously injured and were receiving treatment.
Fifty-four suspects have been arrested in connection with the violent protest.
Police said the protesters were heavily armed and they violently attacked innocent citizens and police on duty in Abuja’s Central Business District.
They said protesters set on fire two vehicles and the National Emergency Management Agency (NEMA) Response Post close to the Federal Secretariat.
Police opened fire with live ammunition as well as tear gas, while protesters threw petrol bombs at the officers, AFP reported.
The confrontations sparked tension in the area, and workers fled. Some motorists who were near the area abandoned their vehicles and also fled for safety.
Authorities redirected motorists and other people away from the area, urging them to use alternative routes as police quelled the unrest.
Amnesty International condemned the police action as a "reckless use of force", AFP reported.
"This new crackdown is part of a shocking pattern in which security forces have used live ammunition to disperse IMN supporters who are simply exercising their freedom of expression," AFP quotes the rights group.
GENESIS OF PROTESTS
The IMN group demanded the release of Zakzaky, who has been in custody since December 2015.
He is facing trial at the Federal High Court in Kaduna, in northern Nigeria, over the killing of more than 300 people, during a religious march in 2015.
Rights groups say some 350 mostly unarmed Shiite marchers were killed by the Nigerian army and buried in mass graves. The military denies the claim.
A panel set up to investigate the clash recommended the trial of Zakzaky and some of his followers.
In a similar clash with the army in 2014, Zakzaky’s three sons were killed.
About 45 Shiite protesters who stormed the premises of the National Assembly last week were arrested.
The IMN have held almost daily marches in the capital in recent months amid concerns Zakzaky's health is deteriorating.
The hostility between the authorities and IMN members remains unresolved as the group vows to keep protesting on the streets until its leader is released, BBC reported.
The IMN, which emerged as a student movement in the late 1970s, was inspired by the Islamic revolution in Iran.
- Additional reporting by BBC and AFP