Update, 8:40 a.m.: Pakistani officials say the siege at the school is over; authorities are sweeping the buildings.
PESHAWAR, Pakistan -- Taliban gunmen stormed a military-run school in the northwestern Pakistani city of Peshawar on Tuesday, killing 126 people, officials said, in the worst attack to hit the country in years.
The overwhelming majority of the victims were students at the army public school, which has children and teenagers in grades 1-10. Pakistani Prime Minister Nawaz Sharif condemned the assault and rushed to Peshawar to show his support for the victims.
The horrific attack, carried out by a relatively small number of militants from the Tehreek-e-Taliban, a Pakistani militant group trying to overthrow the government, also sent dozens of wounded flooding into local hospitals as terrified parents searched for their children.
"My son was in uniform in the morning. He is in a casket now," wailed one parent, Tahir Ali, as he came to the hospital to collect the body of his 14-year-old son Abdullah. "My son was my dream. My dream has been killed."
The attack began in the morning hours, with about half a dozen gunmen entering the school — and shooting at random, said police officer Javed Khan. Army commandos quickly arrived at the scene and started exchanging fire with the gunmen, he said. Students wearing their green school uniforms could be seen on Pakistani television, fleeing the area.
Outside the school, two loud booms of unknown origin were heard coming from the scene in the early afternoon, as Pakistani troops battled with the attackers. Armored personnel carriers were deployed around the school grounds, and a Pakistani military helicopter circled overhead.
Details were sketchy in the face of the overwhelming tragedy. Pakistani television showed soldiers surrounding the area and pushing people back. Ambulances streamed from the area to local hospitals.
The operation appeared to be winding down in the early evening. Pakistani military spokesman, Asim Bajwa, said on Twitter that the operation to clear the school was "closing up." He said 11 more staff members had been rescued from inside the school.
The information minister for the province, Mushtaq Ghani, said 126 people were killed in the attack. Most of the dead were students, children and teenagers from the school, he said. Hospital officials said earlier that at least one teacher and a paramilitary soldier were among the dead.
Pervez Khattak, the chief minister of the province where Peshawar is located, said fighting was still underway in some parts of the school.
The prime minister vowed that the country would not be cowed by the violence and that the military would continue with an aggressive operation launched in June in the North Waziristan tribal area to rout militants.
"The fight will continue. No one should have any doubt about it," Sharif said.
It was not clear how many students and staff remained still inside the facility. A student who escaped and a police official on the scene earlier said that at one point, about 200 students were being held hostage. Both spoke on condition of anonymity because they were not authorized to talk to media.
One of the wounded students, Abdullah Jamal, said that he was with a group of 8th, 9th and 10th graders who were getting first-aid instructions and training with a team of Pakistani army medics when the violence began for real.
When the shooting started, Jamal, who was shot in the leg, said nobody knew what was going on in the first few seconds.
"Then I saw children falling down who were crying and screaming. I also fell down. I learned later that I have got a bullet," he said, speaking from his hospital bed.
Another student, Amir Mateen, said they locked the door from the inside when they heard the shooting but gunmen blasted through the door anyway and started shooting.
The school is located on the edge of a military cantonment in Peshawar, but the bulk of the students are civilian.
There was conflicting information about how many attackers carried out the violence, but it was a relatively small number.
Taliban spokesman Mohammed Khurasani claimed responsibility for the attack in a phone call to media, saying that six suicide bombers had carried out the attack in revenge for the killings of Taliban members at the hands of Pakistani authorities. But the chief minister said there were eight attackers, dressed in military uniforms. Two were killed by security forces and one blew himself up, Khattak said. The rest were still fighting.
Peshawar has been the target of frequent militant attacks in the past but has seen a relative lull recently.
The Pakistani military launched the military operation in the nearby North Waziristan tribal area in June, vowing that it would go after all militant groups that had been operating in the region. With the launch of the operation, security officials and civilians feared a backlash by militants targeted by the military but until Tuesday, a widespread backlash had failed to materialize.
Tuesday's attack calls into question whether the militants have been crippled by the military or will be able to regroup. This appeared to be the worst attack in Pakistan since the 2008 suicide bombing in the port city of Karachi killed 150 people.
The violence also underscored the vulnerability of Pakistani schools, which was dramatically exposed in the attack two years ago on Malala Yousafzai, a Pakistani girl shot in the head by a Taliban gunman outside her school in Swat Valley for daring to speak up about girls' rights. She survived, becoming a Nobel Prize laureate and global advocate for girls' education but out of security concerns has never returned to Pakistan.
Militants have also blown up schools in the northwest.
"I am heartbroken by this senseless and cold blooded act of terror in Peshawar that is unfolding before us," said Malala in a statement. "I, along with millions of others around the world, mourn these children, my brothers and sisters, but we will never be defeated."
Associated Press writers Asif Shahzad and Rebecca Santana in Islamabad, and Danica Kirka in London contributed to this report.