More than 50 people are dead and scores wounded in a series of suspected bomb blasts in India's capital, Delhi.
Two near-simultaneous blasts took place in markets in central and south Delhi, crowded with people shopping ahead of religious festivals next week.
The third blast occurred in the area of Govindpuri which is in the southern part of the city.
Prime Minister Manmohan Singh blamed "terrorists" for the blasts and said he would not tolerate militant violence.
No-one has yet admitted carrying out the explosions.
Officials say more than 50 people are confirmed dead. At least 80 more are being treated in hospital, 10 of whom are in critical condition.
Most of those killed died in the blast at the southern Sarojini Nagar market, they say.
A number also reportedly died in the first explosion, minutes before, in the crowded central neighbourhood of Paharganj, an area close to Delhi's main railway station and popular with Western backpackers.
Some reports say the Govindpuri blast was a bus bomb and that three people died, although this could not be confirmed.
Prime Minister Singh cut short his visit to the north-east to return to Delhi, urging people to remain calm.
In a brief televised address, he said: "These are dastardly acts of terrorism. We are resolute in our commitment to fighting terrorism in all forms."
India's home ministry has convened an emergency meeting of security and intelligence officials and all major markets in the city have been ordered to close.
India's long-term rival Pakistan condemned the explosions.
Its foreign ministry said in a statement: "Pakistan strongly condemns the terrorist attacks in Delhi, which have resulted in the loss of a number of innocent lives.
"The attack in a crowded market place is a criminal act of terrorism."
Many shops were damaged in the market blasts.
"The blast was so powerful, my house shook," Kiran Mohan, a photo editor who lives about 200m (650 ft) away from Sarojini market, told Associated Press.
Babu Lal Khandelwal, a shop owner in Paharganj, said: "There was black smoke everywhere. When the smoke cleared and I could see, there were people bloody and people lying in the street."
Sarojini Nagar shopkeeper, Bansi Lal, said: "There were two foreigners who were on fire and they were begging me to help them. But I was in a daze. I could not help them."
The BBC's Paul Danahar, who was at the site of the blast in Sarojini Nagar, says the scene was one of carnage and confusion.
Most of the people affected were ordinary people out shopping in the festival season, he says.
Both the Hindu festival of lights known as Diwali and the Muslim festival of Eid fall next week.
In May one person died and 49 were wounded by bombs at two Delhi cinemas - an attack blamed on Sikh militants.