PESHAWAR, Pakistan -- Gunmen clad in black have killed more than 130 people at a military-run school in Peshawar, most of them children, in a devastating assault claimed by the Pakistani Taliban.
Heavy gunfire and blasts rang out from the school, where hundreds of students and staff remained hours after the attack began while army personnel and anguished parents surrounded the building in the northwestern Pakistani city's high-security zone.
The office of the provincial chief minister, Pervez Khattak, said at least 132 people including 125 children were confirmed dead and as many children were wounded in the attack, one of the deadliest by militants in Pakistan.
Hours after it began, security officials said government forces had killed five Taliban attackers and that a sixth blew himself up inside the school.
"6th terrorist killed in last block," Major General Asim Bajwa tweeted hours after the attack began. "IEDs (bombs) planted by terrorists hamper speed of clearance."
"Closing up," he tweeted.
Khattak, the most senior elected official in Khyber Pakhtunkhwa Province, had said earlier at least 84 children and 30 adults were killed.
He said about eight to 10 "terrorists" entered the Army Public School and College in midmorning and "opened indiscriminate gunfire."
A student in 10th grade, who gave his name as Ebad, said he had seen dozens of schoolmates killed.
"It was 10:30 this morning when we were called to the auditorium to get first aid training by an army colonel. When we arrived, the firing started, and they entered the auditorium," he said of the attackers. "They killed ... many students. I saw about 40 to 50 students killed in front of me, and they fired on the colonel."
He said he had seen four or five attackers wearing plain black clothing.
A Tehrik-e-Taliban Pakistan (TTP) spokesman who called himself Muhammad Khorasani phoned a Radio Mashaal correspondent and claimed responsibility for the attack, saying it was revenge for the army operation in North Waziristan.
The Pakistani military says it has killed more than 1,100 Islamist militants in North Waziristan since it launched an offensive there in June using air strikes, artillery, mortar fire and ground troops.
Pakistani Prime Minister Nawaz Sharif said he was traveling to Peshawar, and a three-day mourning period was announced for the province that includes Peshawar.
"I can't stay back in Islamabad. This is a national tragedy unleashed by savages. These were my children," Sharif said in a statement.
"This is my loss. This is the nation's loss. I am leaving for Peshawar now, and I will supervise this operation myself."
Sharif also announced a three-day nationwide mourning period over the attack and said parliamentary parties will meet on December 17 in Peshawar to discuss the region's security issues.
Reuters quoted Khorasani as saying, "We selected the army's school for the attack because the government is targeting our families and females."
"We want them to feel the pain."
Khorasani told Reuters the attackers had "instructions not to harm the children but to target the army personnel."
But authorities said most of those killed were children, some of whom were rushed to hospitals by ambulance as the siege continued and helicopters buzzed overhead.
Military officials at the scene said at least six armed men had entered the school and about 500 students and teachers were believed to be inside when the attack began.
The Taliban say they sent in six gunmen wearing suicide vests.
Three heavy explosions were heard hours after the attack began.
The Pakistani military says it had killed four attackers and was searching for other gunmen.
"Remaining clearance in progress," the military said in a tweet. But security personnel at the site told reporters some attackers had escaped.
Jamshed Khan, a school bus driver, said he was standing outside the school when the attack began. He said that "firing suddenly started and there was chaos everywhere and the screams of children and teachers."
A teacher told a private television station the attack occurred during exams. "We were in the examination hall when the attack took place," he said. "Now the army men are clearing the classes one by one."
The attack was one of the deadliest ever at a school worldwide.
More than 330 people, most of them children, were killed when Islamist militants seized a school in the southern Russian town of Beslan in 2004.
With reporting by Reuters, AP, AFP, dpa and dawn.com