The assault at Model Town was brief, and involved four attackers opening fire on worshippers before exploding hand grenades, Bhutta said.
'Well co-ordinated attack'
Bhutta said the death toll at Garhi Shahu was higher because three attackers blew themselves up with suicide vests packed with explosives when police tried to enter the building.
TV footage showed that one assailant had clambered atop the minaret of one of the mosques and was throwing hand grenades.
"They fought the police for some time, but on seeing they were being defeated they exploded themselves," he said.
Police later arrested two attackers.
Daniyal Hassan, a reporter for the Pakistani Dawn News, near one of the attack sites, told Al Jazeera: "The worshipers were busy with their prayers and heard gunfire and some explosions, which I believe were used as a diversion to scare away the security guards outside.
"The crossfire between police officials and attackers continued for about 30 to 45 minutes. The injured have been taken to hospital.
"It [was] a well co-ordinated attack."
Shahbaz Sharif, the chief minister of Punjab province, where the attacks took place, appealed for calm after the fighting. He said the incidents would generate greater resolve to fight "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," he told a news conference.
"We, our security forces will fight this menace till the end.
"Attacks on places of worship is barbarianism. It is a shame to cause bloodshed in mosques."
Target of discrimination
Ahmadi Muslims have been targeted by Sunni groups and suffered discrimination in Pakistan in the past.
They call themselves Muslims but believe that Muhammad was not the final prophet. This view contradicts a central Islamic belief.
Lahore is the second largest city in the country and a vital military and political centre. It has been the scene of several attacks by opposition groups.
Raza Rumi, a policy analyst and editor of Pakistan's weekly Friday Times publication in Lahore said the attack marked a "very sad day" for both the city and Pakistan as a whole.
"The way this minority sect has been hounded for the past three decades has come to such a pass that you now have acts of violence even in private spaces of worship," he told Al Jazeera.
"Their rights to worship and pray are not being adhered to.
"Since the late 19th century, their founder declared himself to be a messiah or prophet of sorts. In Islam, the finality of Prophet Muhammad as the final prophet is part of the Muslim belief system.
"So the Ahmadis were deviating from that and that has always irked fundamentalist Muslims.
"[However] not just moderate Muslims, but even the very devout and staunch Muslims of Pakistan do not support this act of terror."