Story highlights Bangladesh begins two days of mourning

Attack occurred as the holy month of Ramadan nears its end

Dhaka, Bangladesh (CNN) As Ramadan comes to a close, Bangladesh is remembering the victims of this weekend's deadly terror attack at a cafe in Dhaka.

Bangladeshi Prime Minister Sheikh Hasina declared two days of national mourning that started Sunday.

Gunmen killed 21 hostages and two police officers late Friday and early Saturday before authorities raided the restaurant and ended the standoff.

The massacre occurred during the holy month of Ramadan, at the end of the day when Muslims would have been breaking their daily fast. The holiday is set to end Tuesday evening.

"We don't want these terrorists in Bangladesh," the Prime Minister said. "This type of situation is a first in Bangladesh, until now they were committing individual murders. But now suddenly they created this type of situation. What they did here was a very heinous act."

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Bangladeshi troops stormed the cafe early Saturday morning, ending a nearly 11-hour siege. The attack took place in the city's diplomatic enclave, and those killed were from around the globe : Italian, Japanese, Indian, Bangladeshi and an American, according to the country's Joint Force Command. The attack In a statement ISIS claimed responsibility, but Bangladeshi officials said the attack was carried out by homegrown militants and hinted towards a group called Jamaatul Mujahideen Bangladesh All the attackers in the deadly assault on a cafe in Dhaka were Bangladeshi citizens. Five were militants that police had tried to arrest previously, Police Inspector General Shahidul Hoque said. The sole surviving attacker "remains hospitalized," Information Minister Hasanul Haq Inu told CNN Sunday. Haq Inu said investigators have not yet been able to interview him due to injuries sustained during the raid. He did not give specifics on what the injuries are. JUST WATCHED Report: Commandos storm Dhaka restaurant Replay More Videos ... MUST WATCH Report: Commandos storm Dhaka restaurant 01:35 The attack was the deadliest and boldest act of terror in a country that has become increasingly numb to ever-escalating violence by Islamist militants. The victims were among roughly three dozen people taken hostage when attackers stormed the cafe Friday evening with guns, explosives and sharp weapons, authorities said. Some guests and workers managed to escape. Bangladesh attack 21: Hostages killed

13: Hostages rescued 2: Police officers killed 4: Terrorists killed 1: Terrorist in custody 11: Hours of siege Cafe worker Shumon Reza said he saw six to eight gunmen enter the bakery. He escaped as they came in. "The guests were all lying on the ground under the chairs and tables," Reza told Boishakhi TV. And we (the employees) escaped in whichever safe way we could. Some went to the roof, others went to other safe spots." Shortly after, Reza said, the attackers started throwing explosives , one after another. "We thought it wasn't safe anymore and jumped from the roof," he said. CNN Map

Early Saturday morning, military commandos moved in. By the end, 13 people had been rescued and 21 were dead, officials said.

Four terrorists were killed and one was captured alive, police said.

Police had originally identified Saiful Islam Chowkidar as another slain attacker, but owners of Holey Artisan bakery said he was actually a cook at the restaurant.

On Tuesday, police said they had mistaken the cook for a terrorist when in fact he was a victim. Police said they did not kill Chowkidar, but misidentified him after his body was found.

ISIS claims attack

Bangladeshi officials say ISIS is not present in their country, despite the group's claim of responsibility. Bangladesh Information Minister Hasanul Haq Inu said the attack was carried out by homegrown militants.

Initially, a U.S. official told CNN it was more likely that al Qaeda in the Indian Subcontinent conducted this attack because the group had demonstrated a more capable presence in Dhaka through attacks over the past few months.

But after photos purportedly showing the inside of the cafe and dead hostages were posted on an ISIS-affiliated website, U.S. officials said they are now focused on ISIS as the perpetrator.

JUST WATCHED Bangladeshi army: 'Sharp weapons' used to kill hostages Replay More Videos ... MUST WATCH Bangladeshi army: 'Sharp weapons' used to kill hostages 01:55

The photos were posted on Amaq while the siege was ongoing, with a claim that the extremely graphic images were of foreigners killed by terrorists in the attack.

The fact that the images were posted approximately 90 minutes before Bangladeshi forces stormed the restaurant suggest that several hostages had already been killed before the commandos moved in. While CNN can't verify the authenticity of the photos, the images show wall murals, glossy tables with carved legs, white chairs and other items very similar to those seen on the cafe website.

These photos don't prove that ISIS had operational control of the attack, but the website also displayed the photos and noms de guerre of five individuals, claiming they carried it out.

The investigation

Japan has sent Vice Foreign Minister Seiji Kihara, along with a team of terrorism experts, to Dhaka.

Abinta Kabir

The country's victims were corporate employees having dinner with management consultant Tamaoki Watanabe, one of the survivors, said Japanese Chief cabinet secretary Yoshihide Suga.

Watanabe and three other Almec VPI employees were on a project for Japan International Corporation Agency, a government-funded organization for international development and cooperation, according to an Almec statement.

Victims' nationalities Italy: 9 Japan: 7 Bangladesh: 2 India: 1 U.S.: 1

The company does not yet know the fate of the other three employees, according to the statement.

The Japanese government, which is not disclosing names at this point, said it would arrange a government flight for the families of victims as early as Sunday.

The bakery

Even in a country that has become increasingly numb to Islamist attacks, the Holey Artisan Bakery standoff was particularly jolting in its brazenness.

The gunmen went into the bakery on a Friday, the holiest day of the week in Islam, and at a time when the devout would be sitting down to break their fast in the holy month of Ramadan.

And they targeted not a bar or a club -- the kinds of venues fundamentalist Muslims rail against -- but a bakery in the city's Gulshan district, one of Dhaka's most affluent neighborhoods and a diplomatic enclave.

Residents in the neighborhood expressed shock because the upscale neighborhood was considered safe with buildings behind walls, gated driveways and security guard booths.