An explosion occurred on Tuesday evening at Al-Alim Mosque in Gomboru Market, Maiduguri, during Maghrib prayers.
The blast caused panic in the area as worshippers were observing evening prayers inside the mosque.
Witnesses said the mosque has a capacity of more than 50 people and was filled at the time of the incident.
Sources confirmed that one person has been declared dead at the University of Maiduguri Teaching Hospital.
Many others sustained varying degrees of injuries and were rushed to different health facilities across the city.
Some of the injured are receiving treatment at the State Specialist Hospital.
Others were taken to private nursing homes for emergency care.
Victims were also admitted to the Trauma Centre, where doctors are attending to the critically injured.
The exact nature of the explosion remains unclear as security agencies are yet to confirm whether it was caused by an improvised explosive device or another source.
This incident is the first reported explosion in Maiduguri in over a year.
Security personnel have secured the area as investigations continue.
