Abuja, Nov 10 (IANS): At least 78 students were killed and 45 injured Monday in an explosion that rocked a government school in northeastern Nigeria, a hospital source said.

The explosion took place in the Government Comprehensive Secondary Science School in Potiskum, Yobe state. More than 100 blast victims were rushed to a state-run hospital from the scene of the bomb attack, Xinhua quoted a hospital worker as saying.

"Everyone is confused. The casualty figures are so high," the source said, who claimed to have obtained the given figure from the Potiskum General Hospital register.

The huge explosion went off in Potiskum, a commercial hub of northeastern Nigeria's restive Yobe state, killing scores of students and wounding several others, police spokesperson Emmanuel Ojukwu said.

The spokesperson said the number of casualties could not be immediately confirmed as security personnel have surrounded the scene to secure the school.

The incident occurred early morning as the students lined up for morning assembly and the head teacher was addressing the students.

According to a teacher, a thunderous sound was suddenly heard and there was pandemonium as everyone scampered for safety.

The teacher said many of the victims were burnt beyond recognition.

Police cordoned off the roads leading to the school and the hospital, to forestall further attacks.

There was a bomb scare at the hospital, said another medical employee who helped in receiving the casualties.

No official casualty figures have been given, but witnesses said they saw a number of bodies.

No group has claimed responsibility for the bomb attack. But Boko Haram, an outlawed sect which had claimed responsibility for the killings of thousands and kidnappings in Nigeria since 2009, is believed to be responsible for the attack.