Another blast in BauchI, Four Policemen have been wounded in Bauchi, Northeast Nigeria on Monday after an attack with explosives by unknown men at a security checkpoint.

The Bauchi State police spokesman, Mohammad Barau said that two motorcycle-mounted men threw a parcel containing explosives at a police checkpoint in Bauchi.

Barau did not say if there police are any suspects yet, but similar motorcycle-mounted attacks targeting security officers have been blamed on the radical Muslim sect, Boko Haram in the city of Maiduguri, some 280 miles (450 kilometers) away.

The group has claimed responsibility — in unverified statements — for multiple May blasts that hit Bauchi, killing 18 people.

Boko Haram seeks the strict implementation of Shariah law in northern Nigeria.