Media playback is unsupported on your device Media caption The BBC's Aleem Maqbool visits the scene of Malala's shooting in the town of Mingora

People in Pakistan have been observing a day of prayer for the recovery of a 14-year-old girl shot in the head by Taliban gunmen.

Malala Yousafzai was transferred to a military hospital in Rawalpindi on Thursday. Doctors say her progress over the next few days will be "critical".

The girl wrote a diary about suffering under the Taliban and was accused by them of "promoting secularism".

Police said they had arrested four people in connection with the attack.

They were among about 100 people rounded up this week, most of whom were later released on bail.

The suspected mastermind of the attack remains at large.

Meanwhile, Pakistani officials said they had intercepted a telephone conversation suggesting Taliban militants were planning attacks against the media over their coverage of the shooting. The Taliban had earlier said they would target Malala Yousafzai again.

At the scene Here at the hospital in Rawalpindi the security is extremely tight. They do not let anyone enter the wing where Malala is, and a few hours before Prime Minister Raja Pervaz Ashraf's visit, they did not even allow the families of other patients to go in. They didn't let a woman with a bouquet for Malala get close. There are a lot of journalists outside the hospital, but the family is keeping away from the media. The doctors who are attending Malala are not picking up the phone anymore. The press conference with the prime minister was packed with journalists. Everyone was aware of the new threat the Taliban made, but no-one seemed to be afraid of it.

Local officials have offered a 10m rupee ($105,000; £66,000) reward for information leading to the arrest of the attackers.

The shooting has prompted outrage and protests across Pakistan.

On Friday, school children dedicated prayers to her recovery in morning assemblies and she was also remembered during weekly prayers at mosques across the country.

Many prayer leaders condemned the attack, including the chief cleric of Pakistan's largest mosque, Shahi Masjid, in Lahore. He called the young activist an "ambassador of peace and knowledge'".

Schools in the Swat Valley closed on Wednesday - the day after the shooting - in protest at the attack. Rallies have also been held in Islamabad, Peshawar, Lahore, Multan as well as in Malala's hometown of Mingora.

The attack has also drawn widespread international condemnation.

'Critical' hours

Malala Yousafzai was being treated in an intensive care unit in Peshawar before doctors decided to move her to the Armed Forces Institute of Cardiology critical care unit in Rawalpindi.

"Malala's condition is satisfactory, praise be to God, but the next 24 to 36 hours are critical," military spokesman Maj Gen Asim Saleem Bajwa told reporters at a briefing.

"Today is the sacred day of Friday and the entire nation is praying for her health. I pray to Allah that He bestows her with good health very soon," he is quoted as saying by AFP news agency.

The teenager was attacked on Tuesday as she was returning home from school in Mingora in north-western Swat.

Two armed men, on foot, stopped a van packed with about a dozen schoolgirls in a congested area of the town. One of them got into the van and asked which of the girls was Malala Yousafzai before he fired three shots, hitting Malala in the head and injuring two others.

Prime Minister Raja Pervaz Ashraf visited Malala Yousafzai on Friday, the latest politician to do so, and has asked other political leaders to join him in showing solidarity.

Media playback is unsupported on your device Media caption Malala Yousafzai spoke to the BBC in November 2011

Army chief Gen Ashfaq Parvez Kayani, who visited Malala in hospital in Peshawar earlier in the week, said it was time to "stand up to fight the propagators of such barbaric mindset and their sympathisers".

Malala Yousafzai first gained attention aged 11, when she started writing a diary for BBC Urdu about life under the Taliban.

Using the pen-name Gul Makai, she wrote about suffering caused by militants who had taken control of the Swat Valley in 2007 and ordered girls' schools to close.

The Taliban were ousted from Swat in 2009, but her family said they had regularly received death threats.