A gunman opened fire on students after walking into a high school in Potiskum in northeast Nigeria, critically injuring six, witnesses and a humanitarian aid worker said.
It was not immediately possible to ascertain whether the gunman, accompanied by a second attacker, was from Islamist jihadi group Boko Haram but the attack was in their style.
Boko Haram has been trying to carve out an Islamic state in the northeast of Africa's biggest economy for the past six years but Nigerian troops with the help of Chad, Niger and Cameroon are pressing an offensive against the militants.
The gunman, who was caught and beaten by locals, was accompanied by a suicide bomber who detonated but only blew himself up, the sources said.
“We came out from lectures when we saw two people at the gate...he brought out a gun and started shooting,” Musa Ahmed, a student at the College of Administrative and Business studies, said.
“The suicide bomber...detonated the bomb killing himself alone but six of students were shot by the man with the gun.”
Yobe was one of three states where Boko Haram gained control of territory last year. Government troops recaptured key towns in the state in March. The insurgents are now concentrated in Borno state mainly in the Sambisa forest reserve.