ISLAMABAD, Pakistan (CNN) -- A Pakistani teen activist shot by the Taliban was moved to a military hospital in Rawalpindi Thursday in critical condition.

Malala Yousufzai, 14, was flown by helicopter from the military hospital in Peshawar to one in Rawalpindi. 

The latter city houses the headquarters of the Pakistani military, three officials said. They did not want to be identified because they are not authorized to speak to the media about the matter. 

Malala is in "critical" condition, said Lt. Col. Junaid Khan, the head of neurosurgery at the Peshawar hospital. A day before, surgeons removed a bullet lodged in her neck. 

She is also suffering from severe edema, the doctor said. 

Edema is the abnormal accumulation of fluid in part of the body that results in swelling. Doctors said late Wednesday that Malala's condition was "satisfactory."

As she struggled to recover Thursday, the United Nations was marking International Day of the Girl, which is aimed at "highlighting, celebrating, discussing, and advancing girls lives and opportunities across the globe" -- goals that Malala risked her life to pursue. 

Malala's uncle, Faiz Muhammad, said his niece hadn't been conscious or responsive since the surgery to remove the bullet more than 24 hours ago. 

"Doctors say she needs 48-hours' rest," he said.

Muhammad, who is in the hospital with Malala, said the family was "very worried" about her condition.

"We are counting on all the prayers of the nation," he said. "The prayers are with us, so, God willing, everything is going to be fine."

An angry chorus of voices in social media, on the street, in newspapers and over the airwaves decried the attack against Malala as cowardly and an example of a government unable to cope with militants.

On Tuesday, Taliban militants stopped a van carrying three girls, including Malala, on their way home from school in northwestern Pakistan's conservative Swat Valley. 

One of the gunmen asked which one was Malala Yousufzai. When the girls pointed her out, the men opened fire. The bullets struck all three girls. 

The injuries from the shooting were not life-threatening for the two other girls. But the attack put Malala in intensive care.

On Wednesday, police took the van driver and the school guard into custody for questioning. They also said they'd identified the culprits.

Meanwhile, the Taliban claimed responsibility for the attack and vowed to kill her if she survives. The group defended its attack against the girl on religious grounds. 

Anyone who "campaigns against Islam and Shariah (Muslim law) is ordered to be killed by Shariah," the group said in a statement Thursday. 

The group cites precedents for taking such action against children and women.

"It's a clear command of Shariah that any female that by any means plays a role in war against mujahedeen, should be killed," the Taliban said.

Malala "was playing a vital role in bucking up" the Pakistani government and was "inviting Muslims to hate mujahedeen."

"If anyone thinks that Malala is targeted because of education, that's absolutely wrong, and a propaganda of media, Malala is targeted because of her pioneer role in preaching secularism and so-called enlightened moderation," the group said.

Pakistan's picturesque Swat Valley was once one of the nation's biggest tourist destinations. 

The valley, near the Afghanistan border and 186 miles (300 kilometers) from the capital city of Islamabad, boasted the country's only ski resort. It was a draw for trout-fishing enthusiasts and visitors to the ancient Buddhist ruins in the area. But that was before militants -- their faces covered with dark turbans -- unleashed a wave of violence.

They demanded veils for women, beards for men and a ban on music and television. They allowed boys' schools to operate but closed those for girls. 

It was in this climate that Malala reached out to the outside world through her blog posts. 

She took a stand by writing about her daily battle with extremist militants who used fear and intimidation to force girls to stay at home.

Malala's online writing led to her being awarded Pakistan's first National Peace Prize in November. 

The Taliban controlled Malala's valley for years until 2009, when the military cleared it in an operation that also evacuated thousands of families.

But pockets remain, and violence is never far behind.

"I have the right of education," Malala said in a CNN interview last year. "I have the right to play. I have the right to sing. I have the right to talk. I have the right to go to market. I have the right to speak up."

Malala also encouraged other young people to take a stand against the Taliban -- and to not hide in their bedrooms. "God will ask you on the day of judgment where were you when your people were asking you, when your school fellows were asking you, and when your school was asking you that I am being blown up?"

Mian Iftikhar Hussein, the Khyber-Pakhtunkhwa information minister, said he was declaring a bounty of $100,000 for the capture of the culprits in the attempt on Malala's life.

The attack was criticized by governments around the globe.

"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," Jay Carney, the White House spokesman, said Wednesday.

The U.S. government has offered to "provide air ambulance and medical treatment at a facility suitable for her condition if it becomes necessary," he said.

U.N. Secretary-General Ban Ki-moon called the act "heinous and cowardly" on Wednesday and said the attackers must be brought to justice.

"The secretary-general, like many around the world, has been deeply moved by Malala Yousufzai's courageous efforts to promote the fundamental right to education -- enshrined in the Universal Declaration of Human Rights," a representative for Ban said. 

CNN's Shaan Khan, and journalists Aamir Iqbal and Noreen Shams contributed to this report 

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