The slaughter never ends.

(Reuters) – Five explosions at a bus park in northern Nigeria’s main city of Kano killed at least 25 people on Monday, a Reuters witness said, in an area where Islamist sect Boko Haram is waging an insurgency against the government.

The coordinated bombing came as an audio tape emerged of a man saying he was the father of a family of seven French tourists kidnapped by Boko Haram militants.

On the tape he read out a threat by them to increase kidnappings and suicide bombings in Cameroon, if authorities there detain more of the group’s followers.

The blasts in Kano destroyed several buses in the Sabon Gari area, mostly inhabited by immigrants from Nigeria’s largely Christian south, the Reuters witness said. Military and police cordoned off the area after the blasts.

More from the NYT.

ABUJA, Nigeria — Suicide bombers crashed an explosives-laden Volkswagen into a crowded bus on Monday as it was parked at a depot in Kano, northern Nigeria’s largest city, and officials said at least 20 people were killed, possibly many more, as the conflagration spread to four nearby buses.

The attack appeared to be an escalation of the Islamist insurgency that has engulfed half of Nigeria for more than three years.

Flames from the blasts incinerated passengers in the buses, officials said Monday evening, warning that the death toll was likely to rise. Many other people were seriously injured. “It was a suicide attack, and the casualties are massive,” said a senior security official, speaking on the condition of anonymity.

There was no immediate claim of responsibility. But the attack bore the hallmarks of the terrorist group Boko Haram, which has been waging an intermittently bloody insurgency against the Nigerian state, in the name of establishing Islamist rule and Shariah law in the country’s north.