Gunmen suspected of belonging to a radical Islamic sect have shot and killed at least nine women taking part in a polio vaccination drive in northern Nigeria.
The attack highlights the religious tensions surrounding the inoculation of children in one of the few nations where the disease still remains endemic.
The attack shocked residents of Kano, the largest city in Nigeria's predominantly Muslim north, where women often go from house to house to carry out the vaccination drives as Muslim families feel more comfortable allowing them inside their homes than men.
It also signalled a new wave of anger targeting immunisation drives in Nigeria, where clerics once claimed the vaccines were part of a Western plot to sterilise young girls.
The first attack today happened in Kano's Hotoro Hayi neighbourhood and saw gunmen arrive by three-wheel taxis and open fire. At least eight female vaccinators died in that attack, witnesses said. The second attack, in the Unguwa Uku neighbourhood, saw another four people killed.
The witnesses asked not to be named out of fear of angering the radical sect known as Boko Haram.
However, confusion surrounded the death toll, as Kano state police spokesman Musa Magaji Majia said the attacks killed nine people - all of them women taking part in the drive and giving the oral vaccine drops to children. A local hospital later said it received two corpses from the Unguwa Uku attack, with four others wounded.
Definitive death tolls for such attacks in Nigeria are difficult to obtain. Police and military forces in Nigeria routinely downplay such casualties, and families quickly bury the dead before the next sunset per local Muslim traditional.
While police said they had no immediate suspects for the attacks, witnesses said they believed that Boko Haram had been behind the shootings. Boko Haram, whose name means "Western education is sacrilege" in the Hausa language of the north, has been behind a series of violent attacks across northern Nigeria as part of its fight against the country's weak central government.
In December, militants in Pakistan killed at least nine workers on a polio vaccine drive. Militants there have accused health workers of acting as spies for the US, alleging the vaccine is intended to make Muslim children sterile.