ISLAMABAD, Pakistan (CNN) -- A Pakistani army commander was shot and killed by Islamic radicals Sunday during an operation where troops blasted holes in a besieged mosque's perimeter walls, escalating an already tense standoff between troops and the radical Islamists hiding inside.
Lt. Col. Haroon-ul-Islam, a Pakistani army commander, was killed Sunday at the Red Mosque in Islamabad.
Lt. Col. Haroon-ul-Islam was killed and three other officers were wounded during the operation to free women and children holed up inside the Lal Masjid, or Red Mosque, army sources told CNN.
The sounds of sporadic gunfire and heavy explosions punctuated the night air early Sunday, but troops have held back from an all-out assault on the mosque.
They're opting instead to demolish parts of the mosque's perimeter to allow people barricaded inside to escape. Many are women and children who authorities fear are being held as human shields.
The siege, now in its sixth day, is being staged by followers of a radical Islamic cleric, who said from inside the complex they prefer martyrdom to surrender.
That message flies in the face of a warning set forth Saturday by Gen. Pervez Musharraf, Pakistan's president.
"Those who have remained [in the mosque], I request them to come out and surrender. If they don't surrender, they'll be killed ... they must surrender," Musharraf said.
More than 1,200 people, mainly students from the mosque's two Islamic schools, have already fled the compound, but officials don't know how many remain. On Sunday, 164 male students who surrendered three days ago were released to their parents, an Interior Ministry official said.
The cleric leading the standoff inside -- Abdul Rashid Ghazi -- has said there are 1,900 still in the compound. Meanwhile his brother, Maulana Abdul Aziz, said there are only about 850 inside. Aziz, the top cleric at the Red Mosque, was captured Wednesday while trying to slip out of the mosque disguised in a burqa -- the head-to-toe covering worn by some Muslim women.
Interior Minister Aftab Ahmed Khan Sherpao said at least 50 of those still inside are well-armed hard-liners.
Although conditions inside the mosque are unknown, friends and relatives outside the mosque are worried about their loved ones.
"I ask these people to leave my son. We are even ready to pay. My son! My son!" said Mozamil Shah, the father of one young boy still holed up inside the mosque.
In efforts to oust the group, officials have cut off water, gas and electricity to the compound. Officials also disconnected 12 telephones Sunday, but an Interior Ministry official told CNN they had no way of shutting down cell phone service.
Pakistani forces targeted a fuel tank inside the mosque, causing an explosion heard across the capital Saturday, intelligence sources said. The fuel tank had been used for running generators, the sources said.
At least 27 deaths have resulted thus far. Two of those deaths include students who tried to surrender Friday but were shot dead by other students, intelligence sources said. The sources gave no additional details of how the shootings occurred.
Ghazi, one of the mosque's clerics, claimed more than 300 people have been killed since Tuesday, but an Interior Ministry spokesman said the ministry completely rejects that claim.
The violence began Tuesday when about 150 militant Islamic students attacked a police checkpoint close to the mosque. Deadly street clashes quickly erupted, with police firing tear gas at the students and the students fighting back with guns and sticks. They then took refuge in the mosque and an adjoining women's seminary, which the troops subsequently surrounded.
Tensions have been simmering between police and the students at the mosque, who are blamed for a string of recent kidnappings of civilians, Chinese nationals and Pakistani police. The government of Pakistan has been investigating the activities of the mosque, whose students who are demanding to impose Taliban-style rule in the city. E-mail to a friend
CNN's Syed Mohsin Naqvi and Chandrika Narayan contributed to this report