At least 15 policemen have been killed and many more people injured in a suicide bomb attack in Pakistan's capital Islamabad, officials say.
The blast occurred in front of a police station near the city's Melody Market.
It came on the first anniversary of the bloody ending of a siege at the city's Red Mosque, in which more than 100 people were killed during fighting.
The mosque was stormed by Pakistani troops to evict militants who had taken sanctuary within its complex.
President Pervez Musharraf condemned the attack and reiterated the government's commitment to root out terrorism in "all its forms and manifestations".
The White House also denounced the bombing, saying it was a "needless act of violence".
National security spokesman Gordon Johndroe said: "Extremists continue to show their disregard for all human life and their willingness to kill fellow Muslims. We will continue to stand with the people of Pakistan as they face this common enemy."
Police on alert
Chaos in the aftermath of the bomb blast
Security had been tight because of fears of an attack at a rally near the mosque, which is also known as Lal Masjid, where several thousand Islamists had gathered to mark the anniversary.
"The blast happened 15 minutes after the meeting dispersed. A heavy contingent of police was at a main crossing several hundred metres from the mosque and they were targeted in the attack," a senior security official told the AFP news agency.
The bomber managed to conceal explosives under his clothes and get into the secure area, said Mr Malik.
"And from... the outer cordon [of security], where the police force was, there were about 25 officials there, and while people were walking, one of the guys just rushed and blew his suicide jacket," he added.
Blood and body parts covered the streets of this residential neighbourhood as terrified people came running out of their houses, says the BBC's Barbara Plett in Islamabad.
A year ago, Pakistani army commandos stormed the mosque, which had been taken over by pro-Taleban clerics.
Islamist militants responded with a wave of suicide bombings around the country that killed around 1,000 people.
The anniversary demonstration itself was peaceful, but the rhetoric was fiery, with calls for revenge and Muslim holy war.
No organisation has admitted carrying out the attack, but local media reports said the tone of the rally grew more heated after the arrival of banned militant groups suspected of being allied to or inspired by al-Qaeda, our correspondent adds.
Last year, al-Qaeda leaders had called on Pakistani Muslims to avenge the raid.
The bombing comes after a period of relative calm, with the country's newly elected government adopting a strategy of political negotiations and development to try and end Islamic militancy.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.