ABUJA — At least five people have been killed and 35 others have been injured in a bomb blast at a crowded mosque in Nigeria's north-eastern Borno state, police said.

Witnesses said the blast tore through the Gamboru market of Maiduguri, the state capital, on Wednesday as worshippers gathered for evening prayers.

Unverified footage on social media appears to show the aftermath of the explosion, with people stood in a market area with dust particles in the air.

No group has admitted carrying out the attack.

“Preliminary investigations further suggest that the incident may have been a suicide bombing, based on the recovery of fragments of a suspected suicide vest and witness statements recorded, while investigations are ongoing to establish the exact cause and circumstances,” Nahum Daso, spokesperson for Borno state police command, said in a statement.

Daso said police were conducting a sweep of the area in search of secondary devices.

Mosque leader Malam Abuna Yusuf earlier told the AFP news agency that at least eight people had died in the attack, while a militia leader, Babakura Kolo, put the figure at seven.

Another witness, Musa Yusha’u, told AFP that he saw “many victims being taken away for medical treatment”.

Maiduguri has been central to an insurgency by the militant group Boko Haram and its offshoot Islamic State West Africa Province for nearly two decades.

The conflict in northeast Nigeria has killed at least 40,000 people and displaced about two million from their homes since 2009, according to the United Nations.

Though the violence has waned since its peak about a decade ago, it has spilt into neighbouring Niger, Chad and Cameroon.

Concerns are also growing about a resurgence of violence in parts of the northeast, where armed groups remain capable of mounting deadly attacks despite years of sustained military operations. — Agencies