Television images show charred bodies being pulled from the debris of incinerated shops and and bloodied survivors being rushed to receive medical attention.
The first blast ripped through Paharganj, a marketplace along a narrow street that is often filled with Western tourists. Minutes later, the second and deadliest blast went off in Sanjaya Baru, a popular shopping area.
The third explosion happened on a bus when a passenger alerted the driver about a suspicious package. Reports say the driver drove the bus to an isolated area and ordered everyone off. He then tried to throw the bag out the window, triggering the blast.
Authorities say the blasts appear to have targeted heavily populated areas to produce maximum carnage.
Indian Prime Minister Manmohan Singh condemned what he said were acts of terrorism, but said it was too early too know who was responsible. "My heart grieves for those who have lost their loved ones. I condemn the cynical and premeditated attacks on innocent people. These are dastardly acts of terrorism aimed at the people of our country," Singh said.
Festival Of Lights
The blasts come as Hindus are preparing to celebrate Diwali, or festival of lights, on 1 November. The Muslim Eid al-Fitr, which marks the end of Ramadan, comes later in the week.
Singh said the blasts seemed to be timed to cause unrest days before the festivals.
While India's population is predominantly Hindu, it is also home to a significant Muslim minority.
Police have not officially confirmed an Indian news report that more than 150 people have been detained in raids for suspects who may have carried out the bombings.
Indian television reported a previously unknown Kashmiri militant group called Inqilabi, or "Revolutionary," claimed responsibility for the blasts.
But security experts say only leading Pakistani-based militant groups like Lashkar-e-Taiba or Jaish-e-Mohammed have the organization ability to carry out attacks on yesterday's scale.
The explosions happened hours after India and Pakistan opened negotiations on opening the militarized border in disputed Kashmir to get aid to victims of the recent earthquake that devastated the Himalayan region.
Pakistani officials today said that the two sides have agreed on soon opening the frontier in several areas to allow aid to get through.
Opening the border is a sensitive issue for India because of a 16-year armed insurgency by Islamic militants in Kashmir. India faces opposition from dozens of militant groups, particularly Kashmiri separatists, some of whom also oppose the developing peace process between India and Pakistan.
Pakistan was quick to condemn the attacks in New Delhi.
United Nations Secretary-General Kofi Annan, the European Union, the United States, and China have also condemned the attacks.