(This post was last updated at 2:07 p.m. ET.)

Taliban militants stormed a school in northwest Pakistan on Tuesday, leaving scores of students dead.

Quoting Pakistani officials, multiple media outlets say the death toll is at least 140, including at least 80 students in grades 1 through 10.

A little before 8 p.m. local time, police announced that the operation had ended after the gunmen were killed. Security personnel, police official Abdullah Khan told the AFP, were now in the process of sweeping the rest of the building.

The Associated Press reports that six gunmen entered the Army Public School and Degree College in Peshawar, shooting at random. Police quickly moved in and traded gunfire with the militants. The AP adds:

"Pakistani television showed soldiers surrounding the area and pushing people back. Ambulances streamed from the area to local hospitals. ..."It wasn't clear how many students and staff were still inside the facility. A student who escaped and a police official on the scene earlier said at one point about 200 students were being held hostage."

The New York Times reports that Prime Minister Nawaz Sharif traveled to Peshawar. A spokesman for the Pakistani Taliban claimed responsibility for the attack.

The spokesman tells The New York Times the Taliban said they were retaliating for a recent military offensive.

Update at 2:06 p.m. ET. 145 Dead:

Citing government officials, Dawn, the New York Times and the BBC are now putting the death toll at at least 140, most of them children.

Update at 10:15 a.m. ET. U.S. Condemns Attacks:

President Obama issued this statement on the situation in Pakistan:

"The United States condemns in the strongest possible terms today's horrific attack on the Army Public School in Peshawar, Pakistan. Our hearts and prayers go out to the victims, their families, and loved ones. By targeting students and teachers in this heinous attack, terrorists have once again shown their depravity. We stand with the people of Pakistan, and reiterate the commitment of the United States to support the Government of Pakistan in its efforts to combat terrorism and extremism and to promote peace and stability in the region."

Update at 9:39 a.m. ET. Siege Is Over:

The AP, Reuters, Dawn and the Express Tribune are reporting that the siege is over, after all six attackers were killed.

The AFP quotes police official Abdullah Khan as saying "security personnel are carrying out clearance operation and hopefully they will clear the building in a while."

Update at 7:50 a.m. ET. The Heart-wrenching Scene:

The Express Tribune describes the scene:

"Witnesses described how gunmen went from classroom to classroom, shooting children, after a huge blast shook the Army Public School, while some described police struggling to hold back distraught parents trying to break past a cordon and get to the school when three loud explosions went off."Ninth grader Kashan, son of Zaheerudin, told our correspondent, 'We were sitting in the hall and a colonel was giving a lecture when we heard firing from the back.'"Kashan said, 'The sound of the firing kept moving closer when suddenly the door behind us was kicked down and two people started firing indiscriminately.'"The ninth-grader said chaos ensued and the last thing he remembers is children and people falling to the ground. Kashan escaped but with injuries on his feet."

Update at 7:19 a.m. ET. 6 Suspected Gunmen Killed:

Gen. Asim Bajwa, a Pakistani military spokesman, has been tweeting updates of the standoff. In his latest missive, Bajwa says that six terrorists have been killed, and children and teachers continue to be rescued.

"IEDs planted by terrorists hamper speed of clearance," Bajwa says.

Update at 7:12 a.m. ET. Country Should Not Lose Its Strength:

Dawn newspaper reports that as Prime Minister Nawaz Sharif arrived in Peshawar, he said the country is now experiencing the blowback of its offensive against the Taliban and other militant groups in North Waziristan.

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