Indian Prime Minister Manmohan Singh has vowed to defeat those responsible for bomb attacks that killed at least 45 people and wounded 160 others in Ahmedabad.
Mr. Singh and Congress Party leader Sonia Gandhi met wounded bomb survivors in the western city Monday.
Speaking at a bomb-hit hospital, Mr. Singh said the "terrorist" attacks aimed to destroy India's social fabric and communal harmony.
A group called the "Indian Mujahedin" has claimed responsibility for the 16 coordinated explosions that rocked Ahmedabad, in Gujarat state, Saturday.
In an email, the group said it was seeking revenge for Gujarat. It was an apparent reference to sectarian riots in which Hindu mobs killed about 2,000 mostly Muslim people six years ago.
Police are questioning several people, including a member of the banned Students' Islamic Movement of India, which was linked to the riots.
On Sunday, police in Mumbai raided the home of a U.S. citizen, believing a computer there had sent the email. It is unclear if the American is a suspect.
The Ahmedabad attacks were the second deadly bombings in India in two days. On Friday, a series of bombs killed at least one person in Bangalore.
It is unclear if the attacks were related.
Some information for this report was provided by AFP, AP and Reuters.