ISIS claimed responsibility for the blasts in which at least one person was killed and 80 others were wounded early on Saturday in bomb attacks on the main Shiite shrine in the old part of the Bangladeshi capital, Dhaka.
Unidentified attackers threw home-made bombs at thousands of Shiite Muslims as they gathered for a procession to mark the holy day of Ashura, police said.
The attacks took place as 25,000 people gathered at Hossaini Dalan, an important 17th century center of learning for the Shiite community as Shiites around the world marked the month Muharram, which is considered to be holy in Shiite belief.
Police officers said a 14-year-old boy died after three small bombs were thrown at about 2:00 am local time on Saturday (2000 GMT on Friday) and about 50 wounded people were treated at local hospitals.
"Some 50 were brought to the Dhaka Medical College Hospital. A 14-year-old boy was brought in dead. He died due to the explosion," police inspector Mozammel Hoque said, adding that most of the wounded were hit by bomb splinters but none of those taken to hospital were in critical condition.
"There were some 20,000 people in and outside the building at that time. They were preparing to hold the annual Muharram mourning procession when the three [bombs] were exploded," deputy commissioner of Dhaka Police Mofiz Uddin Ahmed told Agece France Presse.
Police said it was the first time that the minority Shiite community in Bangladesh had been targeted and the attacks came just weeks after an Italian aid worker and a Japanese farmer were killed in armed attacks claimed by ISIS.
"This is not a militant attack, rather it is a planned and destructive attack aiming only to destabilize the situation of the country," Asaduzzaman Khan, Bangladesh's home minister told Reuters.
At least five bombs were reportedly thrown, three exploded and two were recovered.
"We've recovered two unexploded bombs. These are like explosive devices and almost like grenades and fitted with batteries," local police chief Azizul Haq said.
Four suspects were reportedly arrested at the scene immediately and the police questioned them. They have not yet released any information about the possible identity of the suspects.
"Given the nature of attacks, I think this has been done to create chaos in the country. It is sabotage," said Dhaka's senior police official Asaduzzamn Mia.
"But it is clear that it was a planned attack."
On Friday, 24 people were killed after two suicide blasts during a procession to mark Ashura in the Pakistani province of Sindh. The blasts targeted Shiites in the city of Jacobabad, also left 20 people wounded.
Bangladeshi Home Minister Asaduzzaman Khan dismissed parallels with the suicide attack in Pakistan saying, "Though the attack came hours after a suicide bombing in Pakistan, we strongly believe the situation [in Bangladesh] is not similar at all as we live peacefully with Shia community."
However, soon after monitoring group SITE reported that ISIS released a meesage saying "soldiers of the Caliphate in Bangladesh" detonated the bombs in Dhaka.
The month of Muharram marks the starting of a new year in the Islamic calender. It is also connected to the Battle of Karbala, in which Imam Hussein ibn Ali, the grandson of Prophet Muhammad, was killed by the army of the second Umayyad caliph Yazid in Karbala, Iraq. During Ashura, Muslims mourn the death of Imam Hussein.