132 are said to be children
UN Secretary-General Ban Ki-moon describes the the attack as "an act of horror and rank cowardice."
Reactions from around the world to Pakistan school attack
The White House said in a statement that the United States condemns the "horrific" attack and reiterated support for the Pakistani government's efforts "to combat extremism and terrorism."
President Ashraf Ghani of neighboring Afghanistan said in a statement "The killing of innocent children is contrary to Islam."
French President Francois Hollande condemned what he described as a "vile" attack, and pledged support for Pakistan's government in the fight "against terrorism."
Foreign Minister Frank-Walter Steinmeier said Germany condemned the attack "in the sharpest possible terms."
Nobel Peace Prize winner Malala Yousafzai, a native of Pakistan, said she was "heartbroken by what she called a "senseless and cold-blooded act of terror."
David Griffiths, Amnesty International's Deputy Director for Asia-Pacific, said, "There can be absolutely no justification for targeting children in this way."
Meanwhile, Pakistani Prime Minister Nawaz Sharif on December 16 vowed to continue an ongoing anti-Taliban operation in the region "until the terrorism is rooted out."
Military source tells Reuters 9 militants were killed in operation to free school today
Gripping survivor accounts coming in