The Islamists, who carried out Bangladesh's terror worst attack at a cafe in Dhaka, had slaughtered all the 20 hostages within 20 minutes of the brazen assault, a top police official said.
Inspector General of Police AKM Shahidul Haque also rejected allegations by the media that police delayed the rescue operation.
"Many media are reporting that we had delayed the rescue mission but we did not. We completed the mission within 12 hours while countries like Kenya took four days to fight similar incident at one of their shopping malls."
"The gunmen had killed the hostages within 20 minutes of the attack," he said.
Islamic State has claimed responsibility for the killing of the 20 hostages and two police officers during the 12-hour siege that ended after the army stormed the Holey Artisan Bakery popular with expats in the diplomatic zone, killing six attackers and capturing one alive.
Hostages who were killed include 19-year-old Indian girl Tarishi Jain. Nine Italians, seven Japanese, one American of Bangladeshi origin, and two Bangladeshis were also among the people who were killed.
Image: Relatives carry the coffin of a victim who was killed in the attack on the Holey Artisan Bakery and the O'Kitchen restaurant, after a memorial ceremony, in Dhaka. Photograph: Adnan Abidi/Reuters