London (CNN) -- The parents of Pakistani teen activist Malala Yousafzai arrived Thursday in Britain to reunite with their daughter, who has become an international symbol of courage after being shot by the Taliban for demanding education for girls.
The 15-year-old, who at times has been unconscious, is being treated in a Birmingham hospital for a gunshot wound to the head.
Her father, Ziauddin Yousafzai, has been a central influence for Malala. He ran a school in Pakistan's conservative Swat Valley that kept its doors open to girls -- in defiance of the Taliban.
Her parents' arrival on Thursday came 10 days after Malala was flown to Britain.
Malala has been unable to speak because a tube has been inserted into her trachea to protect her airway, which was swollen after her injury.
"I am leaving this country with a heavy heart and in extraordinary circumstances because the whole country knows that it is essential that I be with my daughter during her recovery," her father told Pakistani network PTV before leaving Islamabad, in his first public remarks since the October 9 shooting.
"With the nation's prayers she survived the attack and she will surely recover and her health will progress. And, God willing, as soon as she is recovered, I will be back in Pakistan."
Khushal Khan, Malala's younger brother, called for the nation to rally behind his sister. "I want to tell all my friends to pray for Malala," he said.
Malala has been thinking about school even while she lies in her hospital bed, Interior Minister Rehman Malik told reporters after meeting with her family -- she asked her father to take her school books with him.
"The mission she has taken forward and the education awareness that has spread across Pakistan is all Malala's doing," he said, according to PTV. "So I think that our entire nation should be proud of her love for the soil of her country."
After Malala recovers and returns to Pakistan, he said, "we will provide her with complete security, despite anyone's refusal, to ensure that something like this never happens again. The attack on Malala was a mindset of people who don't want to see this country progress."
Pakistan President Asif Ali Zardari has spoken with the girl's father, asking him to stay in Britain as long as necessary while his daughter recovers, Rehman Malik said.
Malala has been communicating with medical staff by writing notes, the hospital has said.
As of Thursday, Malala "continued to respond well to treatment," the hospital's website said.
She is expected to need "a significant period of rest and recuperation" before undergoing reconstructive surgery, Dr. Dave Rosser, medical director of University Hospitals Birmingham, said last week. That surgery could involve reinserting a piece of her own skull or fitting her with a titanium plate.
Malala was fighting an infection, but was able to move her extremities and has stood with help from nurses, the hospital said.
Although the bullet grazed her brain as it passed from above her eye into her shoulder, she understands where she is and seems to be functioning well intellectually, it added.
Malala sent a message of thanks to the thousands of people in Pakistan and elsewhere who have attended rallies and vigils honoring her courage and praying for her recovery.
The Taliban have claimed responsibility for the shooting, but don't appear to have anticipated the level of condemnation it would provoke.
Malala initially gained international attention in 2009, as the Taliban gained a foothold in her home region of Swat, a Taliban redoubt in northwest Pakistan, near Afghanistan.
On her blog, Malala wrote about her life in the region, a center of militant activity where girls schools were shuttered and strict Islamist rules imposed. In her writings, which earned her Pakistan's first National Peace Prize, she encouraged young people to oppose the Taliban.
Pakistani police said Wednesday that six men have been arrested in Swat in connection with Malala's shooting, but the primary suspect remained at large.
Police have identified Atta Ullah Khan, a 23-year-old man from the district where she was attacked, as the primary suspect. Police said they were searching for Khan, who was studying for a master's degree in chemistry.
CNN's Jonathan Wald and Shaan Khan contributed to this report.