The Taliban gunman, who boarded the girl’s school bus which was taking children home from school, asked for her by her name before firing shots at her head and neck, news agencies reported.
Yousufzai was moved to a military hospital in Peshawar in a helicopter. Though her wounds were reportedly not life-threatening, a provincial information minister said a medical board which examined the girl considered the next few days to be critical, the Associated Press reported.
Surgeons are reported to have successfully removed a bullet Wednesday morning.
Yousufzai started writing a blog for BBC under the pseudonym Gul Makai when she was 11 and has been vocal about the need to educate females ever since.
When the Taliban became the de facto rulers of the Swat region between 2003 and 2009, schools were ordered to be closed as part of their edict banning girls' education.
Yousufzai, then 11, wrote in a blog published by the BBC: "My friend came to me and said, 'for God's sake, answer me honestly, is our school going to be attacked by the Taliban?'”
“I had a terrible dream yesterday with military helicopters and the Taleban,” she wrote Jan. 3, 2009. “I have had such dreams since the launch of the military operation in Swat. I was afraid going to school because the Taleban had issued an edict banning all girls from attending schools. Only 11 students attended the class out of 27,” she wrote.
“On my way from school to home I heard a man saying 'I will kill you'. I hastened my pace and after a while I looked back if the man was still coming behind me. But to my utter relief he was talking on his mobile and must have been threatening someone else over the phone,” she wrote.
The Pakistani army launched an offensive and retook control of the Swat valley in late 2009, and the ninth-grader received the country's highest civilian award in recognition of her courage.
She was also shortlisted for the International Children Peace Prize, awarded by the Dutch organization KidsRights, last year.
The Taliban have claimed the responsibility for the attack on the ninth-grader Yousafzai. "This was a new chapter of obscenity, and we have to finish this chapter," Taliban spokesman Ahsanullah Ahsan told the AP over the phone.
"She was pro-West, she was speaking against Taliban and she was calling President Obama her ideal leader," Ahsan told Reuters over the phone. "She was young but she was promoting Western culture,” he said.
Pakistani Prime Minister Raja Pervaiz Ashraf condemned the attack and called her a daughter of Pakistan. U.S. State Department spokeswoman Victoria Nuland said, "Directing violence at children is barbaric.”
“It’s cowardly. And our hearts go out to her and the others who were wounded, as well as their families,” Nuland said.