Isolated shots rang out as a group of worried parents entered a besieged mosque in Islamabad on Friday to collect children caught up in a deadly standoff between Islamic radical students and security forces.
A cleric leading the Taliban-style movement at Red Mosque said overnight that he and hundreds of followers were willing to surrender, but the government insisted on unconditional surrender after three days of violence in which 19 people have died.
The government said the attempt to attach demands, including safe passage, was unacceptable and insisted cleric Abdul Rashid Ghazi release women and children being held as human shields.
President Pervez Musharraf has told security agencies to be patient in order to keep casualties down and allow maximum time for parents to take daughters out of a madrasa in the same compound, officials said.
Violence erupted outside the Red Mosque, in the capital on Tuesday after months of rising tension between authorities and two cleric brothers heading the mosque.
Ghazi's elder brother, Abdul Aziz, was caught on Wednesday trying to flee disguised in a woman's all-covering burqa. Still dressed in a burqa for an extraordinary interview on state television, Aziz called on his followers to give up.
About 1,200 students have now come out. Aziz said there were still some 850 students inside, including 600 women and girls, and around 15 men were armed. However, Ghazi later put the total number of students at 1,900.
According to Interior Minister Ahmed Aftab Khan Sherpao, however, there were between 50 and 80 hard-core militants armed with automatic weapons, grenades and petrol bombs.
Hundreds of troops and police are surrounding the fortified compound housing the mosque and a madrasa in a leafy central Islamabad neighbourhood.
Water, gas and electricity supplies have been cut off.
A siege plan has existed for some time, and information gathered on the mosque's layout and its defenders fighting strength, but the plan only kicked in after the clashes erupted.
There was intermittent gunfire and explosions on Thursday and early on Friday. Interior Ministry spokesman Javed Iqbal Cheema said troops had blasted some holes in the compound walls.
Minutes after the group of around 25 parents entered the compound at around 8.00 am (0300 GMT), sporadic shooting was heard. Over an hour later they were still inside.
Ghazi told television channels by telephone from the mosque that he wanted safe passage for himself and his followers.
"There are no militants from banned organisations among the students," Ghazi told Aaj Television.
He later told Geo TV that students coming out could be checked to see none was a militant, "They should announce a ceasefire and come here and discuss a screening process."
He also asked that he and his sick mother be allowed to live in the mosque "until I make some alternative arrangements".
But the government insisted on unconditional surrender.
"If he is sincere in his offer then first of all he should immediately release the women, girls and innocent children who are being kept there forcefully," Cheema told a news conference.
"They should leave their weapons in the mosque and come out."
Many Pakistanis welcomed the action against a movement reminiscent of the Taliban in Afghanistan.
Moderate politicians and the media have for months urged Musharraf to tackle the Red Mosque radicals, but he cited concern about bloodshed and authorities tried to appease them.
Musharraf, who has been under pressure from Western allies to do more to tackle militancy, faces an election this year and while a peaceful and successful end to the stand-off would win him credit, heavy casualties in an assault would be damaging.
The clerics and their followers, most of whom are in their 20s and 30s, launched an increasingly provocative campaign from January to press various demands, including action against vice. They threatened suicide attacks if suppressed.
But it was last month's kidnapping of six women and a man from China -- Pakistan's most steadfast ally -- whom the students said were involved in prostitution, that was a key factor forcing government action.