Bangladeshi militants were behind the hostage crisis in Dhaka that left 20 civilians dead, a top police official said, denying any link with the Islamic State extremist group.
Twenty civilians, most of them foreigners, were killed by Islamist militants who took them hostage during an hours-long siege that started Friday at a restaurant in the Bangladeshi capital.
Bangladeshi troops stormed the Holey Artisan Bakery restaurant in Dhaka's diplomatic zone early Saturday to end the siege, and killed six terrorists. Two police officers were also killed.
Inspector General of Police Shahidul Hoque told reporters that the attackers had no link with Islamic State and that five of the six dead militants had been on the watch list of law enforcement agencies.
"Police were in the hunt to arrest them and there were drives to nab them several times. They are all Bangladeshi militants," Hoque was quoted as saying by the state-run Bangladesh Sangbad Sangstha news agency.
Police released photographs of the bodies of the attackers hours after the rescue operation.
The authorities on Sunday launched an investigation into the bloody siege.
Forensic experts from the Criminal Investigation Department (CID) and National Security Agency were at the Holey Artisan Bakery, where the terrorists were holed up overnight Friday, to search for clues.
"We have launched the search to find evidence to know more about the attackers," CID officer Abul Hasan told reporters outside the scene.
Troops managed to recover the bodies of the 20 civilians, who included Italians, Japanese, Bangladeshi, American and Indian nationals.
Thirteen civilians were rescued during the operation.
Prime Minister Sheikh Hasina, who announced two days of mourning starting Sunday, vowed that her government will track down the terrorists and their patrons.
"We must find out the roots of the culprits who gave arms and explosives to the terrorists for committing the barbaric attack on the restaurant," she said when Japanese State Minister for Foreign Affairs Seiji Kihara called on her Sunday.
The national flag was flown at half-mast atop all public buildings and black flags were hoisted as the country mourned the victims of the deadliest terrorist attack on Bangladeshi soil.
A statement circulated online Saturday by apparent supporters of Islamic State claimed responsibility for the attack.
The statement, whose authenticity dpa could not verify, said that five Islamic State fighters had attacked "a gathering of subjects of the crusader states in the city of Dakka in Bangladesh."
It claimed that they had killed 22 "crusaders" including seven Italians and threatened that "subjects of the crusader states" would not be safe anywhere "as long as their aircraft are killing Muslims."