Updated

Nigerian police say three policemen have been killed by suspected Islamic militants in Katsina, a northern state outside the region in which the militants usually operate.

Police spokesman Aminu Abubakar says they were killed Monday while pursuing four gunmen on motorcycles who attacked a checkpoint on a road from Katsina to Kano, Nigeria's second-largest city.

Three states in northern Nigeria have been under emergency rule for nine months due to massacres by suspected Islamic militants. Over the last weekend alone, more than 120 people were killed in three separate attacks in northern Nigeria.

Officials and residents blame Boko Haram, a militant group that preaches a harsh version of Islamic law and has killed thousands in 4 1/2 years of insurgency.