At least 141 people, mostly children, were killed when Taliban suicide attackers stormed the school and began firing indiscriminately at students and teachers yesterday in one of the most shocking Taliban attacks in recent memory.
"There can be absolutely no justification for targeting children in this way. This unconscionable Taliban attack is a grave reminder that civilians in north-west Pakistan desperately need effective protection from militant groups," said David Griffiths, Amnesty International's Deputy Director for Asia-Pacific.
A Taliban spokesman said the attack was in response to recent Pakistani army operations in nearby North Waziristan, where hundreds of Taliban fighters were killed.
The Taliban have targeted students in Pakistan on numerous occasions, but this is by far their deadliest attack on a school.
Since 2010, there have been at least four attacks on school buses - including the one in which Nobel Peace Prize winner Malala Yousufzai was shot in the head in Swat in 2012.