A third blast hit worshippers in the city of Kaduna about half an hour later .
The first two blasts occurred within minutes of each other and targeted two churches in the city of Zaria , according to Kaduna State police chief Mohammed Jinjiri .
A third blast hit worshippers in the city of Kaduna State about half an hour later .
The first two blasts occurred within minutes of each other and targeted two churches in the city of Zaria , according to Kaduna State police chief Mohammed Jinjiri .