Some 400 small bomb blasts have rattled Dhaka and other cities across Bangladesh, killing two people and injuring more than 100 others.
Police say the homemade bombs, which went off almost simultaneously, did not cause major damage anywhere and appeared to be aimed at spreading fear and panic.
Authorities have issued security alerts all over the country but have not been able to identify the bombers, though police said some 45 suspects had been detained.
Police say they suspect an outlawed Islamic group -- Jamatul Mujahedin Bangladesh -- whose leaflets were found at some of the blast sites.
The group wants Islamic rule in Bangladesh -- a predominantly Muslim country with a secular constitution.
The leaflets said the blasts were also to warn the United States and Britain "to vacate Muslim countries, or face Muslim upsurge."