Updated: Bomb explosion rocks Kaduna, at least 15 feared dead

(Reuters) – A bomb tossed off the back of a motorcycle at a Nigerian Muslim cleric killed at least 15 people on a busy commercial road in the northern city of on Wednesday, witnesses said.

The blast scattered debris and dead bodies on the Alkali Road in the city centre, but missed Sheikh , who was conducting Muslim prayers in , two witnesses told Reuters by telephone.

There was no immediate claim of responsibility, but militant group has been staging attacks, especially with explosives, outside its northeastern heartlands in the past three months.

The group has often attacked Muslim leaders and imams who criticise its hardline Salafist ideology.

A Witness , a trader, said that he counted 15 bodies in a police van after the explosion.

Police were not immediately available for comment.

Boko Haram, which is fighting to carve out an Islamic state in , has repeatedly targeted civilians this year, mostly in remote northeastern Borno state. It killed more than 2,000 civilians during the first half of this year, (HRW) estimated a week ago.

The Islamists sacked the northeast town of and surrounding villages over the weekend, killing at least 50 people.

The five-year-old insurgency has been in the international spotlight since fighters kidnapped more than 200 girls from a school in the northeastern village of on April 14th. President met parents of the abducted girls for the first time on Tuesday.