Jamaat activists took to the streets as the party's vice-president Delwar Hossain Sayedee was convicted of "crimes against humanity" back in 1971 when Bangladeshis waged a liberation war against Pakistan.
Justice ATM Fazle Kabir, chairman of the three-judge International Crimes Tribunal-1, ordered the 73-year-old to be "hanged by neck till he is dead".
The main defence counsel Abdur Razzaq alleged that there were some judicial irregularities and accused the tribunal of doing "utmost injustice" to Sayedee.
Jamaat was upset by what it believes is clear political vendetta. Another leader of the party, Abdul Quader Mollah, was handed a life term for committing atrocities during the 1971 war.
Claiming that the verdict against Sayedee is part of the ruling Bangladesh Awami League's efforts to create a rift in the opposition alliance, the Jamaat called for nationwide protests.
Members of the party's student wing Islami Chhatra Shibir and Jamaat activists went on a rampage. They beseiged a police outpost in Sundarganj and torched it after beating three policemen to death. An equal number of arsonists were killed in the resultant police firing.
Awami League supporters in Thakurgaon were also targeted by the Jamaat and Shibir members. Soon, Border Guard Bangladesh (BGB) personnel and policemen arrived at the place to defend the Awami men.
Over 35 people including six policemen were killed and scores of people injured in riots at Rangpur, Satkania, Noakhali, Satkhira, Cox's Bazar, Dinajpur, Chapainawabganj, Natore and Sirajganj on Thursday.
Several incidents of vandalism have been reported from across the country on Friday too. Parts of the capital Dhaka also witnessed violence.
BGB chief major General Aziz Ahmed told newspersons that paramilitary forces have been "deployed in 15 troubled districts" to enable the "civil administration" to restore calm.