Suicide car bombers on Saturday attacked the offices of a Nigerian subsidiary of Indian telecom major Bharti Airtel in the volatile city of Kano besides that of South African firm MTN, killing at least four.

Survivor Bayo Osho said he was at work in the Airtel building located near Mallam Kalto Square in Sabon Gari when two suicide bombers drove separate vehicles into the premises.

According to the survivor, the first car was used to force the gate open and the driver came out and exchanged gun fire with the security personnel before the second one, laden with explosives, drove in.

The explosives went off sending flames and smoke high into the air.

Firefighters battled the fire even as the military cordoned off the area.

Officials from Airtel, one of the three biggest mobile phone service providers in Nigeria, were unavailable for comment.

A local news website, Street Journal, said four persons had died. The Islamist group Boko Haram has in the past targeted phone companies, accusing them of cooperating with the security services.

Boko Haram says it wants to create an Islamic emirate in Muslim-dominated northern Nigeria.

Kano was the scene of Boko Haram’s deadliest attack yet in January, when at least 185 people were killed in coordinated bombings and shootings.

Violence linked to the Boko Haram insurgency is believed to have left some 3,000 people dead in Nigeria since 2009, including killings by the security forces.

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