Indian officials are investigating who may be responsible for a bombing that killed nine people and wounded scores of others late Saturday in the western city of Pune.
The blast struck a bakery popular with tourists.
India's Home Minister, Palaniappan Chidambaram, called the blast at the German Bakery a "significant terrorist incident," though there has been no claim of responsibility.
The attack is the deadliest since the 2008 Mumbai siege blamed on Pakistani militants.
Opposition Hindu nationalist leaders said Sunday the deadly attack in Pune brings into question the government's decision to resume talks with Pakistan.
On Friday, India and arch-rival Pakistan agreed to hold high-level talks in New Delhi on February 25. Ties between the two countries have been strained since the November 2008 siege of Mumbai.
If Saturday's blast is confirmed as a terrorist attack, it would be the first since gunmen, allegedly from the Lashkar-e-Taiba group in Pakistan, carried out coordinated assaults on two hotels and other locations, killing more than 150 people.
The 1,000-year-old city of Pune, also known as Poona, is India's eighth largest city and is located about 100 kilometers from Mumbai.
It attracts yoga practitioners, new age therapists and dancers from around the world, and is home to many institutes of higher education.
U.S. Ambassador to India Timothy Roemer condemned the bombing. The Embassy in New Delhi sent a message to U.S. citizens, advising them to be alert for possible terrorist attacks, noting Saturday's bombing took place at a bakery popular with Westerners.
Some information for this report was provided by AFP, AP and Reuters.