Gunmen attacked worshippers from a minority Muslim sect at two mosques in Lahore on Friday, taking hostages and killing at least 80 people, officials said.
The gunmen opened fire shortly after Friday prayers and threw grenades at two Ahmadi mosques in the residential neighbourhoods of Garhi Shahu and Model Town.
Sajjad Bhutta, deputy commissioner of Lahore, said at least 70 people had been killed in the twin attacks, while 78 were injured.
<b1>The death toll at Garhi Shahu was higher, Bhutta said, because three suicide attackers blew themselves up when police tried to enter the building. Police are still searching the area, as two attackers were still at large.
Punjab Chief Minister Shahbaz Sharif said one attacker had been arrested. Police in Model Town confirmed that one gunman had been arrested and another killed.
There was no immediate claim of responsibility, but suspicion fell on the Pakistani Taliban.
Punjab law minister Rana Sanaullah said the arrested attacker was a teenage Pashtun, which indicated a link to the tribal Waziristan area and hence, to the Taliban.
"They had long beards and were carrying rucksacks," said deputy commissioner Sajjad Bhutta. He said a suicide vest laden with explosives was recovered from the mosque where the attackers escaped.
But a witness gave a different picture of the gunmen. "He was young, clean-shaven," said Rabia Mehmood, a reporter.
"The prayer leader was giving a sermon when we heard firing and blasts. Everybody stood up and then two gunmen barged into the mosque and started spraying bullets," Fateh Sharif, a 19-year-old student who was at the Model Town mosque, said.
Ahmadis are a persecuted minority in Pakistan. The Human Rights Commission of Pakistan said it had warned of threats against the community centre in Lahore for more than a year.
Punjab Chief Minister Shahbaz Sharif said the incidents would generate greater resolve to combat extremism. "It's a reminder to the nation that Pakistan will achieve its destiny only after we get rid of the worst type of extremism and fundamentalism. The entire nation will fight this evil," he said.
Friday's shootings were the worst in Pakistan since the March 12 suicide attacks in Lahore that killed 57 people. Nine attacks have killed more than 220 people in the city in the past year.