A series of bombs exploded Saturday in Bangladesh's capital as a top opposition leader was speaking at a rally from atop a truck, killing at least 16 people and injuring hundreds, witnesses and news reports said.

The main opposition leader, Sheikh Hasina, crouched low in the truck soon after the first blast, which detonated as she was addressing thousands outside her Awami League party's headquarters in central Dhaka. She was visibly shaken but not hurt.

"The investigation is ongoing. The death toll is 16, and, according to reports from various hospitals, more than 150 are injured," a police officer told Reuters.

No one claimed responsibility for the blasts, but the general secretary of the Awami League, Abdul Jalil, said the assailants were targeting Hasina, 57, the main opposition leader, who was Bangladesh's prime minister from 1996 to 2001.

The Awami League has accused Prime Minister Khaleda Zia's government of corruption, incompetence and harassment of political opponents. It has asked Zia to step down and call early elections. Zia's government rejects the allegations and has vowed to remain in power until its five-year term ends in 2006.

Zia condemned the "dastardly attack on a political rally" and said her government will try to find those responsible.

"Let us all work together to prevent repeat of such cowardly attacks," she said in a statement.

Police gave few details, but one of Hasina's aides, Saber Hossain Chowdhury, said the first blast was followed by at least eight other explosions and numerous gunshots, and the car that carried Hasina away had several bullet marks in the rear glass.

"It seemed to me that some of the bombs were thrown from multi-story buildings near the scene," said Farook Khan, an opposition lawmaker who was standing close to Hasina.

Khan estimated that at least 15,000 people were at the rally when the explosions were set off. It had been called to protest a series of explosions this month that killed two people, including an opposition supporter, in the northeastern city of Sylhet.

Activists in Bangladesh's Awami League party are taken to a hospital after bomb blasts shook a rally attended by thousands outside party headquarters. No one claimed responsibility.