Militants armed with assault rifles and grenades have attacked worshippers at two mosques in the Pakistani city of Lahore. Some reports say at least 16 people have been killed.
The police say they have no confirmation on casualty figures, but they say they fear the toll is going to be high.
The gunmen stormed the two mosques in the neighbourhoods of Model Town and Garhi Shahu shortly after Friday prayers. Up to 2,000 worshippers were inside.
Some reports said a large number of hostages were being held.
Numerous explosions were heard at the scene and gunfire continued, with images of at least two gunmen firing at police from the roof of one of the mosques.
The Pakistani newspaper The News reports that there were at least seven gunmen at one of the mosques, and some of them have been shot dead by security forces.
These were Ahmadi mosques, a religious minority group described as a sect in Pakistan, and declared by the authorities to be non-Muslims.
Observers say the Ahmadis have seen their religious rights in mostly Muslim Pakistan curtailed by law.
A group known as the TTP Punjab has reportedly claimed responsibility for the attacks.