New Delhi, Sep. 8 : A day after a powerful brief case place bomb explosion outside the Delhi High Court claimed the lives of eleven people and wounded 76 others, the national capital woke up to a tense morning on Thursday with heavy security still at the blast site and in other prime locations.

Leading national newspapers published front-page articles on the blast, with residents strongly condemning the act.

The explosion of the high-intensity two-kilogram bomb left a three to four feet deep crater near the main reception counter where passes are issued for lawyers and visitors to enter the sprawling sandstone building before the main security checkpoint.

Armed police personnel and officials of the National Investigation Agency (NIA) were seen patrolling the area on Thursday.

Indian authorities are investigating a claim of responsibility allegedly made in the e-mail by the Harkat-ul-Jihad Islami militant group, an al Qaeda affiliate, with bases in Pakistan and Bangladesh. It has claimed responsibility for attacks in India in the past.

Police have reportedly detained three people for questioning on Thursday, including the owner of an internet cafe in the Kishtwar region of Kashmir over an e-mail claiming responsibility for a deadly bombing of the New Delhi High Court.

An attack in broad daylight at such a high-profile location, which lacked CCTV cameras and had faulty security scanners, quickly led critics to question the authorities readiness especially as it came ahead of the September 11, 2001 anniversary of attacks in the United States.

The sight at a hospital in New Delhi, where the injured and dead were taken, was tense as relatives frantically ran around the hospital to find out about the condition of their loved ones.

"The blast is a cowardly act. Innocent people have lost their lives in the blast. This is a very sad event. People behind the act should be punished severely under the law," said Sher Khan, resident of northern Haryana state.

The families of the injured and others in the hospital said there was chaos all around, as the number of people wounded kept increasing.

"The number of injured and dead bodies rose till about 10 pm (local time). Dead bodies were sent to the victims'' family from the hospital. The situation here was bad and there was chaos all around. The state and the federal government were blaming each other for it," said Madhav Parishree, resident of Bareilly district in northern Uttar Pradesh State.

In an e-mail to the NIA, the South Asian militant group called on India to repeal the death sentence of a man convicted in connection with an attack on the Indian parliament in 2001 and warned it would otherwise target major courts in the country.

In May, a low-intensity blast outside the same High Court in Delhi triggered panic but injured no one.

Forensic evidence has initially revealed that the nitrate based explosives had possible traces of pentaerythritol tetranitrate (PETN), a powerful high explosive, which caused the blast, a senior home ministry official said.

Sketches of two suspects have been released to the public.

Several Islamist group have been fighting against Indian rule in the disputed region of Kashmir. (ANI)