Clashes broke out when Hefazat activists tried to break a police cordon.
The street battles went on for hours, with police firing rubber bullets and tear gas and the Islamists hurling crude explosives and chunks of brick.
Syed Ashraful Islam, secretary-general of the ruling Awami League and a government minister, said demonstrators set fire to the Communist Party of Bangladesh office and ransacked several other business establishments in central Dhaka.
Shahriar Shahid, the managing editor of BSS, said the service had to suspend operations for the day after Hefazat activists set a fire at the entrance of its office.
Blame to go around
The government, rights groups say, shares blame not just for its crackdown but also for muffling the free speech of the Islamists.
On Monday, authorities shut down the offices of pro-Islamist Diganta Television and Islami TV stations after they aired footage of the clashes.
"They came in early in the morning and ordered us closed," staffer Tanvir Hussain told CNN.
Information Minister Hasanul Haq Inu told reporters the stations "provoked violence (by) spreading hatred and rumors."
Last month, the government shut down another opposition newspaper.
"This is what I and many others feared when the Shahbag movement started," said Razab Chowdhury, a Bangladeshi expatriate in Fremont, California. "Does it matter that Hefazat is misguided? Does it matter that their vision of Islam is as twisted as the Taliban's?
"Before, I didn't know about these guys; they were a fringe group that pranced about in Chittagong. Now security has stabilized situation, but I fear it is pushing the country closer to a civil war."
Monday morning, the reminders of the weekend violence were everywhere.
Smoke smoldered from rubbish heaps. Fires burned inside ransacked stores. Bricks and rocks littered the streets.
Shopkeepers held up pages from copies of Quran burned in shop fires and wailed, "Those who did this are not Muslims."
Bulldozers pushed the debris to the side.
Bangladesh is still reeling from the aftermath of a catastrophic building collapse last month where the death toll continues to mount: more than 650 by Monday.
And now this.
But Bangladeshis are resilient people.
By Monday afternoon, the rickshaws and the cars were back on the streets in Motijheel. So were the street peddlers and the pedestrians.
The cars blared their horns, the rickshaws squeezed into every available space. The pedestrians flung profanities.
Life, it appeared, was slowly returning to normal.