The police constable killed at the Dainik Bangla intersection during clashes with the BNP was hacked to death by a leader of Jatiyatabadi Chhatra Dal, the party's student wing, according to Home Minister Asaduzzaman Khan Kamal.
"We have images showing a Chhatra Dal leader brutally beating him. He didn't just beat him but also used a knife to wound his head," he told reporters at Dhaka Medical College Hospital on Saturday evening.
“This scene has left a scar on everyone's heart,” he added.
Large numbers of security personnel were deployed in Dhaka in the run-up to duelling rallies by the BNP, the Awami League, and Jamaat-e-Islami in the capital on Saturday.
Jamaat wrapped up its rally in Dhaka's Motijheel despite failing to secure police permission for the gathering, while violent clashes marred a separate rally by the BNP, the largest opposition group.
BNP activists clashed with their Awami League counterparts ahead of the opposition party's rally in Naya Paltan.
Police used tear gas to try and control the situation, but the fracas devolved into rounds of clashes between the factions.
Clashes between the BNP and the police eventually spread to Naya Paltan, Fakirapul and Rajarbagh.
The Rapid Action Battalion said assailants attacked people in parts of the capital, including Kakrail, Naya Paltan, Motijheel, and Fakirapul, and vandalised and torched public and private vehicles.
They targeted Chief Justice Obaidul Hassan’s residence, Central Police Hospital in Rajarbagh, torched ambulances and attacked the residences of senior law-enforcing officials, according to the elite force.
They also assaulted media personnel on duty and vandalised CCTV cameras installed on different roads.
The BNP rally was called off after the clashes that prompted the party to announce a day-long nationwide shutdown for Sunday.
Police said Amirul Parvez, a constable of DMP's CTTC unit, died after suffering an injury to the head at the Dainik Bangla intersection during the clashes.
In the meantime, some videos went viral on Facebook. One video shows a policeman being surrounded and assaulted until he became immobile. In another video, two policemen faced a similar attack.
"You saw how a policeman was brutally attacked and killed. They pelted him with rocks, causing him to fall and then hit him. Brickbats rained down on him,” Asaduzzaman said.
The home minister suggested the attacks were an deliberate attempt to create chaos, similar to what had happened centring the 2014 polls.