Police in Indian-controlled Kashmir said Friday they have detained a man suspected of sending an e-mail claiming responsibility for a bomb blast at New Delhi's High Court that killed at least 12 people.

Earlier Friday, police detained five other people for questioning as they probe rival claims of responsibility for Wednesday's attack. Police arrested the owner of an Internet cafe in Indian-controlled Kashmir, his brother, and an employee. Two college students were also detained.

Authorities received an e-mail attributed to the group Harkat-Ul-Jihad al-Islami shortly after Wednesday's explosion. The message, which was traced to the cafe, warned that other courts in the country would be attacked unless India repealed the death sentence given to a man convicted in connection with the 2001 attack on India's parliament.

On Thursday, the domestic group Indian Mujahideen claimed responsibility for the New Delhi courthouse bombing in a separate e-mail sent to media organizations. The group also threatened to attack a shopping mall next week.

Authorities are investigating the authenticity of both claims. Police have released the sketches of two men seen at the site during the time of the blast, while India's National Investigative Agency has offered more than $10,000 in reward money for information on those responsible.

The bomb exploded Wednesday morning near the High Court's main gate where a crowd had gathered to enter the complex. The blast killed at least 12 people and injured nearly 80 others.

The blast at New Delhi's High Court was the first major terror attack in India since three near-simultaneous bomb blasts targeted India's financial capital, Mumbai, in July, killing some 20 people. No one has been arrested in that case, but authorities say they have focused their investigation on the Indian Mujahideen group.

Wednesday's attack was the second explosion at the High Court this year. In May, a small bomb exploded outside the same court, but did not cause any casualties.