Pakistan gunman in Islamabad stand-off
Part of the heart of the Pakistani capital, Islamabad, has been closed off because a man with two automatic weapons has been firing randomly.
The gunman is accompanied by a woman - possibly his wife - who was travelling in his car with him and two children.
His indiscriminate firing has damaged a police vehicle.
The stand-off is being screened live on at least two Pakistani television stations. He has made a series of incoherent demands.
The BBC's Charles Haviland in Islamabad says that police originally stopped the man for driving on the wrong side of the street.
The man then got out of his car and - using his wife as an intermediary to pass on notes to police - began swinging his weapons around and demanding to see senior officers.
Onlookers
"I am against vulgarity and immorality. My associates have taken up positions in the whole of Pakistan," he told a local TV channel while making various other incoherent demands.
Our correspondent says there is strong criticism on Twitter of some TV channels for giving him so much publicity and for interviewing him live. He is also reported to have said that he will never surrender.
A senior police superintendent has arrived at the scene and has started talking to him, but the gunman continues to get in and out of the car where the children - a boy and a girl - are sitting.
Anti-terrorism police have also arrived on the scene as have hundreds of onlookers who gathered in the central Jinnah Avenue as night fell and occasional gunshots resounded in the air.
A neighbour told TV that the gunman's house had been packed up and that he had hired the car now at the centre of the stand-off.
Correspondents say that security has been tight in Islamabad after police were warned about possible attacks by militants based in tribal areas on the border with Afghanistan.
Checkpoints manned by armed police are located at most major access points into the city, which is home to most government buildings and diplomatic missions.
Correspondents say that questions are now certain to be asked as to how the gunman managed to breach security and paralyse the city centre.
BBC News - Pakistan gunman in Islamabad stand-off