Gunmen killed at least 10 people when they attacked a Shiite Muslim mosque in the northern Pakistani city of Rawalpindi in the first major sectarian attack since a nationwide crackdown on extremism was launched last month.
Three men armed with automatic weapons drove on motorcycles to the Shah-Najaf mosque about 7:00 pm (1400 GMT) before two went inside, bolted the door and fired indiscriminately at about 28 worshippers, police said.
"I heard gun shots and fell down. When I turned back, I saw two young boys, one (was) loading a gun magazine while the other was firing at namazis (worshippers)," one of the survivors told the state-run Associated Press of Pakistan.
City police chief Marwat Ali Shah told AFP 10 people were killed in the attack and about a dozen others were injured. He said the gunmen escaped.
Shah said police had cordoned off all entrances to Rawalpindi, the twin city of Pakistan's capital, Islamabad.
President Pervez Musharraf expressed "profound shock and grief" at the attack and offered his condolences to the families of the victims.
He ordered federal and provincial police to investigate and vowed to hunt down the attackers.
"Those responsible would be unearthed and given exemplary punishment," he said.
Such acts would only renew the resolve of the government and the people of Pakistan in rooting out extremists, he said.
Interior Secretary Tasneem Noorani called it "a very reprehensible attack".
"This clearly appears to be a sectarian attack. It (sectarianism) has been curbed in the past, but to expect that everything will fall in line is expecting too much," Noorani told AFP.
"But we are determined to wipe out this terrorism from Pakistan and will continue to make our best efforts.
"This government will do whatever needs to be done to prevent such attacks and bring the culprits to justice."
More than 2,000 people have been killed over the past decade in sectarian violence in Sunni Muslim-majority Pakistan.
Shiites make up about 20 percent of the nation's population.
Hundreds of people converged at the mosque after the shooting, looking at the ghastly scene quietly and without incident.
The mosque was splattered with blood and worshippers' skullcaps littered the floor.
Bullet impacts were seen on the walls and the floor, with the bullets' casings lying on the floor.
It was the first communal attack since Musharraf announced on January 12 a crackdown on Islamic extremism and sectarianism.
In his announcement, Musharraf banned the Sunni extremist group Sipah-i-Sahaba Pakistan and its Shiite counterpart, Tehreek-i-Jafria Pakistan.
Both groups are accused of fomenting violence between the country's two major religious sects.
"Sectarian terrorism has been going on for years. Every one of us is fed up of it. It is becoming unbearable," Musharraf said in his speech.
"The day of reckoning has come.
"Do we want Pakistan to become a theocratic state? Do we believe that religious education alone is enough for governance or do we want Pakistan to emerge as a progressive and dynamic Islamic welfare state?
"The verdict of the masses is in favour of a progressive Islamic state."
After the attack, a grieving father who lost one son demanded the attackers be brought to justice but criticized the government for not doing enough to crack down on extremists.
"I want justice. We want to be peaceful but our patience is running out. This is our limit," Gulzar Ahmed Kazmi, 59, told AFP at the Holy Family hospital.
"The government has failed to protect us. The terrorist groups, Sipah-i-Sahaba and Lashkar-i-Jhangvi, have been killing us for many years now."
Kazmi's 22-year-old son, Kamran, died in the shooting while another son, Imran, 25, was critically wounded.