One person has been killed and two wounded when gunmen opened fire at a mosque in the Pakistani port city of Karachi.
At least 250 worshippers were at the Sunni mosque for morning prayers, when the attackers struck.
Police said it was unclear whether it was "an act of terrorism or the result of personal enmity".
There has been a series of attacks at mosques in the city, blamed on outlawed Sunni and Shia groups.
The attack took place at a mosque in the Bangali Para district of the city at about 0630 (0130GMT).
"Two men in a yellow taxi cab pulled up outside the Mohammadi Mosque and opened fire with a pistol at the prayer leader," said Karachi police chief Fayyaz Leghari, according to the AFP news agency.
"Someone started shooting during the prayers," said Mufti Farooq Ahmed Siddiqui, who was wounded in the leg.
"I only heard gunshots on my back ... then the people started running."
A Sunni cleric, Mufti Mohammed Jamil, was shot dead in the city last month, and twin bomb attacks at a mosque killed five in August.
Dozens of people were hurt in the blasts, which came after two people died on Saturday in a bombing outside a car rental office in Karachi.
But it is not known if the explosions are connected.
Senior police officials say Sunday's blasts were highly-planned and co-ordinated, in which two explosive devices were used to hit as many people as possible.
No group has said it carried out the attack.
The school has had problems with sectarian violence in the past.
In May, its leader, Mufti Nizamuddin Shamzai - a prominent supporter of Afghanistan's former Taleban regime - was killed in a drive-by shooting.
Thousands of his supporters rioted following his death.