Indian police officers prepare to cover the scene of a blast outside the High Court in New Delhi, India, September 7, 2011.

Indian authorities are calling the suspected bomb blast outside the High Court building in New Delhi a deliberate terror attack after it killed at least nine people and wounded 62 others.

Police say they believe the "medium intensity bomb" was hidden in a briefcase near a main gate to the building. The blast struck Wednesday morning as people gathered outside, waiting to enter the courthouse.

Speaking from Bangladesh, Indian Prime Minister Manmohan Singh condemned the act as "cowardly," urging Indians to stand together so that the "scourge of terrorism is crushed."

Indian Home Minister P. Chidambaram visited the scene, and said top national investigation teams are working on it.

He said that so far, it is not possible to identify who was responsible, and there have been no immediate claims of responsibility.

It is the first major terror attack in India since near-simultaneous triple 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 domestic Indian Mujahideen militant group.

Wednesday's blast also is 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.