A wounded Pakistani student receives treatment at a hospital following an attack by Taliban gunmen on a school in Peshawar on December 16, 2014. Taliban insurgents killed at least 130 people, most of them children, after storming an army-run school in Pakistan December 16 in one of the country's bloodiest attacks in recent years. A Majeed/AFP/Getty Images

Update as of 8:17 a.m. EST: All six Taliban militants who launched an attack on an army-run school in Peshawar are now dead and the Pakistani army is winding up operations, a report said, citing Reuters.

Update as of 6:37 a.m. EST: The Pakistani army’s Special Forces rescued two children and two staff members from the school, which has been attacked by Taliban insurgents, Reuters reported, adding that at least five of the six militants had been killed.

Meanwhile, Imran Khan, chairman of Pakistan Tehreek-e-Insaf, said that he would postpone a protest planned for Dec. 18 in Peshawar, Dunya News, a local news agency, reported. Khan also condemned the attack in Peshawar, stating: "Those who stoop so low, you cannot even have any words to describe what they are."

Update as of 6:05 a.m. EST: At least 126 people, including over 100 children, have reportedly been killed in a Taliban attack at an army-run school, Reuters reported Tuesday, citing Pakistani security officials. Nearly 122 people have been injured in the raid while an unknown number of children are still being held hostage inside the building.

Four of the six suspected militants have also been killed by the Pakistani army, according to media reports. Meanwhile, Indian Prime Minister Narendra Modi condemned the attack, calling it a “cowardly terrorist attack.”

Update as of 5:08 a.m. EST: According to reports citing the Pakistani military, Taliban gunmen are holding children hostage inside a Peshawar school that was raided earlier in the day.

According to The Express Tribune, a local news agency, 10 men in uniforms resembling those of the Frontier Corps, a paramilitary unit of the Pakistani army, had entered the school. The report added that security forces had killed two militants while one had blown himself up.

British Prime Minister David Cameron wrote on his Twitter account: "The news from Pakistan is deeply shocking. It's horrifying that children are being killed simply for going to school."

Update as of 4:15 a.m. EST: The death toll in an attack on a school in Peshawar, Pakistan, has risen to over 100 people, including 84 children, according to Pervez Khattak, chief minister of Khyber Pakhtunkhwa province.

The Pakistani Taliban took responsibility for the raid on the army-run school, making it one of the deadliest attacks in the region. According to reports, six militants armed with suicide vests attacked the school. The group later said that the attack was in retaliation for the Pakistani army's offensive against the group in the country's northwest.

“The army is trying hard to bring the situation under control,” a senior government official told Dawn News. “The operation is currently underway.”

Meanwhile, Pakistani Prime Minister Nawaz Sharif has reportedly departed for Peshawar to supervise the ongoing operation against the Taliban militants.

Update as of 3:17 a.m. EST: At least 21 people, including 20 students and 1 security officer, were killed in a Taliban suicide attack on an army-run school in Peshawar, Pakistan, The Associated Press reported Tuesday.

At least 14 people, including 12 children, a Pakistani army soldier and a teacher, were killed and over 40 were injured after Taliban gunmen stormed an army-run school in the Pakistani city of Peshawar -- the capital of the restive Khyber Pakhtunkhwa province in the country’s northwest -- on Tuesday. The militants, believed to be at least six in number, have also taken at least 500 students hostage, according to local media reports.

The school has been cordoned off by the Pakistani army and rescue operations are currently underway. Ambulances are transporting wounded children to hospital, according to local media reports. Militants of the Pakistani Taliban reportedly claimed responsibility for the attack.

“Our suicide bombers successfully entered the army school in Peshawar this morning. We are giving them direct instructions to not harm minors,” Muhammad Khorasani, a spokesperson for the Tehreek-e-Taliban Pakistan (TTP) told The Express Tribune, a Pakistani daily, adding that the Pakistani army’s operation, targeting Taliban strongholds in the country’s northwest, had “forced us to take such an extreme step.”

Pakistani Prime Minister Nawaz Sharif condemned the attack and said that “those behind the heinous act will not be spared,” according to local media reports.