Thousands of security officials are patrolling the streets of Bangladesh's capital to prevent violence as the main opposition party and its 17 allies try to enforce a daylong national strike. The opposition is calling for changes to the election process.

Local media is reporting that at least three homemade bombs have been set off in Dhaka during Wednesday's shutdown. No injuries have been reported.

Opposition spokesman Shamsuzzaman Dudu accused authorities of detaining some opposition activists in parts of the country.

Schools and most businesses were shut in Dhaka and traffic was thin.

The opposition wants a caretaker government to oversee national elections due early next year.