Nobel Peace Prize winner Malala Yousafzai says she is heartbroken by the news that the Taliban launched a vicious attack on a school in the northwestern city of Peshawar.

At least 120 people were killed in the attack on the school for children of the military. Most of them are children between ten and 15 years old. Dozens more were injured.

Local hospitals appealed for blood donations for the dozens of others who were wounded in the most deadly insurgency Pakistan has seen in years.

Six Taliban gunmen struck the school, armed with bombs and guns, and began shooting children at random.

Military reports say all six were killed.

Malala was also shot by the Taliban for her campaign for education. She calls the attack a “cold-blooded act of terror” against innocent children, and says, “I — like millions of others around the world — mourn these children, my brothers and sisters. But,” she says, “we will never be defeated.”