Two blasts rocked northern Nigeria's Kaduna city on Wednesday, killing at least 25 people, in what appeared to be a double bomb attack by Boko Haram Islamists.
Police blamed the first explosion on a suicide bomber targeting the convoy of a prominent cleric who has publicly criticised the Islamic extremists waging a deadly five-year uprising.
Sheikh Dahiru Bauchi was travelling in an open-roofed truck greeting well-wishers who had assembled on the roadside when the bomb went off at roughly 12:30 pm (1130 GMT), Kaduna police chief Umar Shehu said.
"Twenty-five people have so far been confirmed dead," he told AFP.
Bauchi, who had just presided over a major Koranic conference, escaped unhurt but his convoy was splattered with the blood and flesh of the bomber and his victims, according to witness Mustapha Sani.
There was no immediate confirmation of Boko Haram's involvement in the attack on the Isa Kaita road near the city centre.
But the Islamists, who have killed more than 2,000 civilians already this year, have accused senior clerics like Bauchi of betraying the faith by submitting to the authority of a secular government, currently led by a devout Christian, President Goodluck Jonathan.
Roughly two hours later a second blast rocked the crowded Kawo area on the outskirts of Kaduna, a commuter hub full of bus stations that also hosts a military post.
While police were not yet ready to describe the second explosion as a bombing, witnesses at the site who spoke to AFP anonymously said it too was deliberate.
Rescue workers were racing to the chaotic scene, just a few kilometres from where the cleric's convoy was attacked, witnesses said.
- Sectarian clashes -
Boko Haram has claimed the killing of several clerics across the north, while assassination attempts targeting Nigeria's second and third most powerful Islamic leaders have both failed.
Kaduna, once the north's political capital, has seen relatively little Boko Haram violence in the last 12 months.
Suicide blasts targeting churches in 2012, blamed on the militant group, sparked sectarian clashes in the religiously divided city that left hundreds dead.
If carried out by Boko Haram, the latest violence will underscore the growing threat the extremists pose to Africa's most populous country and top oil producer.
Islamist gunmen have in recent months attacked civilians at will across the remote northeast, the group's historic stronghold, but 2014 has also seen major unrest in key urban centres.
The capital Abuja has been hit by three separate bombings, while a double car bombing in the key central city of Jos killed at least 118 people in May.
Jonathan, facing unprecedented pressure to contain the bloodshed, has asked parliament to approve a $1 billion foreign loan to upgrade the security services.
Some analysts have described the request as a tacit acknowledgement by the president that his military is overmatched by Boko Haram who are blamed for killing more than 10,000 people since 2009.