Islamic militants attacked a boarding school in northeast Nigeria before dawn Saturday, killing 29 students and one teacher.
Some of the pupils were burned alive in the latest school attack blamed on a radical terror group, survivors said.
Parents screamed in anguish as they tried to identify the charred and gunshot victims.
Farmer Malam Abdullahi found the bodies of two of his sons, a 10-year-old shot in the back as he apparently tried to run away, and a 12-year-old shot in the chest.
"That's it, I'm taking my other boys out of school," he told The Associated Press as he wept over the two corpses. He said he had three younger children in a nearby school.
"It's not safe," he said. "The gunmen are attacking schools and there is no protection for students despite all the soldiers."
Survivors at the Potiskum General Hospital and its mortuary said gunmen attacked Government Secondary School in Mamudo village, 3 miles from Potiskum town at about 3 a.m. Saturday.
The gunmen are believed to be from the Boko Haram sect whose name means "Western education is sacrilege."
They killed 29 students and an English teacher Mohammed Musa, who was shot in the chest, according to another teacher, Ibrahim Abdu.
"We were sleeping when we heard gunshots. When I woke up, someone was pointing a gun at me," said 15-year-old Musa Hassan.
He put his arm up in defense, and suffered a gunshot that blew off all four fingers on his right hand, the one he uses to write with.
He said the gunmen came armed with jerry cans of fuel that they used to torch the school's administrative block and one of the hostels.
"They burned the children alive," he said, the horror showing in his wide eyes.
He and teachers at the morgue said dozens of children from the 1,200-student school escaped into the bush but have not been seen since.
Some bodies are so charred they could not be identified, so many parents do not know if their children survived or died.
Islamic militants from Boko Haram and breakaway groups have killed more than 1,600 civilians in suicide bombings and other attacks since 2010, according to an Associated Press count.
Scores of schools have been burned down in the past year in northeast Nigeria.
President Goodluck Jonathan declared a state of emergency May 14, and deployed thousands of troops to halt the insurgency, acknowledging that militants had taken control of some towns and villages.
The military has claimed success in regaining control of the area — the states of Adamawa, Borno and Yobe . However, the area covers some 155,000 square kilometers (60,000 square miles) or one-sixth of the sprawling country.
Soldiers say they have killed and arrested hundreds of fighters.
But the crackdown, including attacks with fighter jets and helicopter gunships on militant camps, appears to have driven the extremists into rocky mountains with caves, from which they emerge to attack schools and markets.
The militants have increasingly targeted civilians, including health workers on vaccination campaigns, teachers and government workers.
Farmers have been driven from their land by the extremists and by military roadblocks, raising the specter of a food shortage to add to the woes of a people already hampered by the military's shutdown of cell phone service and ban on using satellite telephones.