ISLAMABAD, Pakistan – Government troops stormed the compound of Islamabad’s Red Mosque before dawn Tuesday, prompting a fierce firefight with militants accused of holding 150 hostages inside, officials said. At least 40 rebels and three soldiers were killed.

Amid the sounds of rolling explosions, commandos attacked from three directions at about 4 a.m. and quickly cleared the ground floor of the mosque, army spokesman Gen. Waheed Arshad said. Some 20 children who rushed toward the advancing troops were brought to safety, he said.

Two dozen others fleeing were captured by security forces, Arshad said, without giving further details about those trapped inside. Another military official, who spoke on condition of anonymity because he was not authorized to talk to the press, later said that 51 militants had surrendered or been captured.

The mosque itself has been cleared of the militants – who are armed with machine guns, rocket launchers and gasoline bombs. They put up tough resistance from the basement of the mosque, Arshad said. He said rebels were also firing from minarets and have booby trapped some areas. “Those who surrender will be arrested, but the others will be treated as combatants and killed,” he said.

Five hours after the assault began, resistance remained in parts of the compound. Gunfire and explosions still boomed in the city.

Pakistan’s Religious Affairs Minister Mohammed Ijaz ul-Haq – quoting the mosque’s leader – said foreign militants were among the defenders. He did not give the numbers or their nationalities.

The assault began minutes after a delegation led by a former prime minister left the area declaring that efforts to negotiate a peaceful end to a week-old siege had failed.

Clashes this month between security forces and supporters of the mosque’s hard-line clerics prompted the siege. The religious extremists had been trying to impose Taliban-style morality in the capital through a six-month campaign of kidnappings and threats. At least 67 people have been killed since July 3.

An associate of the mosque’s chief cleric, Abdul Rashid Ghazi, told the private Geo Television network that troops had seized the mosque but that resistance was continuing from inside the religious school.

The aide, Abdul Rahman, said he did not know what had happened to Ghazi, who was at a different location within the compound.

The assault was signaled by blasts and gunfire. About three and a half hours after the assault started, Arshad said 50 to 60 percent of the complex had been “cleared” but resistance continued in “various places.”

Associated Press writers Zarar Khan and Sadaqat Jan in Islamabad and Habibullah Khan in Khar contributed to this report