India's cities have been put on high alert, with fears of more attacks after at least 46 people were killed in two days of bombings. A little-known group claimed responsibility for a series of blasts in the western city of Ahmadabad that came one day after bombings in the southern city of Bangalore.
Security has been stepped up at markets, hospitals, airports, and train stations in cities around the country.
In New Delhi, police used loudspeakers and distributed leaflets in crowded market places, warning people to watch out for unclaimed baggage and suspicious objects.
The measures came after at least 16 bombs exploded in crowded neighborhoods of Ahmadabad on the evening of July 26, killing at least 45 people and wounding 161. Another set of blasts in the technology hub of Bangalore killed at least one woman on July 25.
Narendra Modi, chief minister of the Gujarat State in which Ahmadabad is located, appealed for calm.
"We will not leave any stone unturned to find out the perpetrators behind this inhuman act," Modi said. "We will see to it they are dealt with strictly. I appeal to the people of Gujarat to remain united and maintain peace."
Police said they had detained dozens of suspects from the Ahmadabad bombings.
A group calling itself the Indian Mujahedeen claimed responsibility for the attack. But in e-mails sent to the media the group reportedly made no mention of the bombings in Bangalore.
The group was unknown before May, when it said it was behind a series of bombings in the western city of Jaipur that killed 61 people.
India has been hit repeatedly by bombings in recent years whose perpetrators rarely claimed responsibility. Officials usually blame the attacks on Islamic militants who allegedly want to provoke violence between India's Hindu majority and Muslim minority.
Ahmadabad residents such as Ajay said an atmosphere of fear loomed large over the historic city despite calls for calm.
"There is an atmosphere of fear. People are afraid and troubled. Everybody is scared," Ajay said. "The new day has brought a hope of a new and better beginning."
In 2002 in Ahmadabad, riots between Muslims and Hindus left about 1,000 people dead.
with agency reports