Police commandos carried out raids across New Delhi, detaining several people believed to be connected to a series of blasts that ripped through the Indian capital, killing at least 20 people and wounding about 100 others, police said Sunday.

A coordinated series of at least five explosions struck a park and crowded shopping areas in New Delhi just after sundown Saturday, a prime time for weekend shoppers in this crowded, chaotic city.

• Click here to see photos from the blasts. (WARNING: Graphic images)

An Islamic militant group claimed responsibility for the bombings in an e-mail sent to several Indian news organizations.

By Sunday morning the death toll had risen to 20, said city police spokesman Rajan Bhagat. At least 98 others were wounded, he said.

Media reports said 10 people had been detained in the overnight raids. Bhagat confirmed only that "several" people had been held. He gave no further details on the suspects' identities or where they had been captured.

"We have collected vital clues and we hope to crack the case soon," said Bhagat.

But his optimism stood in stark contrast to India's record in solving other bombings that have hit the country in recent months.

Police have made little headway in finding those behind a series of bombings in the western city of Jaipur in May that killed 61 people or the July blasts in the western state of Gujarat that killed at least 45.

Both of those attacks were claimed by the Indian Mujahideen, a previously unknown group, who also claimed responsibility for Saturday's attacks.

As in their previous attacks, the group sent a number of Indian media outlets an e-mail message just before the blasts Saturday evening warning that India was about to receive "the Message of Death."

"In the name of Allah, Indian Mujahideen strikes back once more. ... Do whatever you can. Stop us if you can," the message said.

After May and July attacks police carried out a series of raids but made no arrests or filed charges.

Nevertheless, Indian officials vowed they would not be not be cowed.

"It's a very cowardly act of violence," Mayor Arti Mehra told reporters near the scene of two of the explosions, in the M-Block market of the city's upscale Greater Kailash neighborhood.

"They want to break the spirit of Delhi. They have tried this in other places before and they have not succeeded and they will not succeed here. They will not scare us," Mehra said.

Home Minister Shivraj Patil said, "We will face this difficulty, we will find out who has done it."

India, a largely Hindu country, has long battled Muslim militant violence in the disputed Himalayan region of Kashmir, the country's only majority Muslim state. It was not clear if the Indian Mujahideen was tied to the Kashmiri groups.

India also has frequently blamed longtime archrival Pakistan for backing Islamic groups, a charge Pakistan denies.

Late Saturday Pakistan condemned the attacks.

"The people and the Government of Pakistan share the pain of the victims and bereaved families," President Asif Ali Zardari and Prime Minister Yousaf Raza Gilani said in a statement.

"Pakistan condemns all terrorist acts perpetrated in any part of the world," the statement said.

U.S. Ambassador David Mulford also condemned the attack.

"There is no justification for the vicious murder of innocent people. The U.S. stands shoulder to shoulder with India in the fight against terror," he said in a statement.

The deadliest explosion was believed to be in Gaffar Market in the city's Karol Bagh neighborhood, a warren of stores popular among wholesalers and bargain-hunters. It exploded on a street jammed with clothing shops and stores that sell cheap mobile phones.

Two of the explosions occurred just 300 yards apart in Connaught Place, the city's central shopping district. The usually crowded streets quickly emptied of shoppers and filled with screaming police cars, fire engines and gawking crowds.

In the minutes after the blast, the scene was filled with blood and chaos, as police officers raced to the scene and passers-by helped victims into taxis and rickshaws to get to hospitals. A sadhu, a Hindu holy man clad in orange robes, lay face down in the gutter a few feet away, apparently dead. Another man walked away from the scene, helped by other men, his face covered with blood.

Raj Kumar, 30, a store clerk in the area, said he was nearby when he heard the explosion.

"Everyone was running every way," he said. "They heard the bomb and they just started running."