At least seven people were killed and several injured after an improvised explosive device detonated in a mosque in Maiduguri, Nigeria, a security source reported. According to Argentina News Agency, the death toll could exceed ten people. Worshippers were praying at around 18:00 local time when the device exploded in the mosque at the Gamboru Main Market, Xinhua news agency was told by a source involved in rescue operations. A thick smoke enveloped the area after the blast, the source added. Police and the army have not yet issued an official statement on the incident.