Since late 2011, Potiskum, about 500 kilometers (300 miles) northeast of Nigeria's central capital, Abuja, has been targeted by Boko Haram fighters in attacks.
Military Spokesman Eli Lazarus told the Reuters news agency that six people were killed in the violence, which happened when "unknown gunmen attempted to attack Potiskum but were repelled by troops".
There were mixed reports initially on where the victims were from, but the police chief of Yobe told CNN they were North Korean physicians assisting at Potiskum General Hospital as part of a government agreement.
The military statement said Mr Zangina was leader of Boko Haram in the "North Central part of Nigeria and co-ordinator of most of the suicide attacks and bombings in Abuja, Kaduna, Kano, Jos and Potiskum".