A bomb blast and subsequent firing by three gunmen at a local government building on the outskirts of Zaria in northern Nigeria killed at least 25 people and civil servants on Tuesday morning, state governor, Nasir el-Rufai, said on his Twitter feed. Militant group Boko Haram is suspected to be behind the attack.
Zinari Shehu, a local radio journalist who was at the scene, said the bomb went off at around 10am (0900 GMT) in Zaria's suburb of Gogarawa, where people had gathered to greet a newly appointed head administrator.
"Three gunmen dressed in black opened fire at the scene inside the secretariat, that was when I ran out," Ibrahim Mohammed, a local government worker, told Reuters.
Responsibility was not claimed immediately but it had hallmarks of Islamist militant group Boko Haram, which has stepped up attacks over the last ten days.
The last major attack in Kaduna state was in July 2014 when at least 82 people were killed by suicide bombers. One of them targeted President Muhammadu Buhari, who was then an opposition leader.
Last week alone, more than 200 people died in a string of attacks. On Sunday, at least 44 people were killed in Jos and on Monday, a suicide bomber failed in an attempt to hit a major mosque in Nigeria's second biggest city of Kano.
Boko Haram has been trying to establish a state adhering to strict sharia law through an insurgency that began in 2009. It controlled a territory larger than Belgium by the end of 2014.
Nigerian and regional forces have joined together to push the jihadists out of most of that territory but the militants have a last stronghold in the Sambisa forest reserve.
With their progressive loss of territory since the start of the year, the militants have returned to their guerrilla tactics of hitting soft targets.