Bangladeshi authorities failed to heed online warnings of an imminent attack in the capital of Dhaka on July 1, reports Reuters.

Hours after the warnings were posted on social media, they became reality when a group of jihadists, allegedly linked to the Islamic State (ISIS/ISIL), massacred 22 people, including two police officers, and wounded another 40 during a nearly 12-hour standoff at the Holey Artisan Bakery cafe in Dhaka that began the night of July 1 and carried into the next day.

“Most of them had been brutally hacked to death with sharp weapons,” said Brig. Gen. Nayeem Ashfaq Chowdhury, a Bangladesh Army spokesman.

The attack has been deemed one of the deadliest in recent Bangladeshi history.

HT Imam, a political adviser to Bangladeshi Prime Minister Sheikh Hasina, told Reuters, “It is to be investigated whether there was an intelligence failure.”

Bangladeshi authorities charged with monitoring social media ignored several warnings posted on Twitter on July 1, saying there would be an attack, indicated Imam, adding that police also underestimated the possibility of the cafe being a potential target.

“The police thought any attack was more likely to target embassies and major hotels and restaurants,” Imam told Reuters, adding that “they [police] didn’t think at all it can be this place.”

“This was the first time in Bangladesh such a thing had taken place. Nobody was prepared for it. They did not realise the gravity of the situation initially,” he also said. “Initial response was slow.”

Although ISIS has claimed responsibility for the attack, some officials doubt the group carried it out.

On Tuesday, ISIS released a propaganda video warning of more attacks.

Police in Bangladesh have warned that anyone sharing, uploading, or liking jihadist-linked online activity would face punishment.

“If someone uploads or shares the video, gives Like for it, or comment in its favour on the social media, the person will face charges,” Deputy Inspector General AKM Shahidur Rahman told bdnews24.com, referring to the ISIS video released Tuesday.

Both ISIS and al-Qaeda in the Indian Subcontinent (AQIS) have been linked to a spate of attacks in Bangladesh over the past 18 months, often involving jihadists using machetes against various individuals, including writers, bloggers, academics, activists, liberals, atheists, foreigners, gays, and religious minorities.

The attacks have occurred despite a nationwide government crackdown on militants that has led to the arrest of more than 14,000 people.

According to The New York Times (NYT), “The authorities in Bangladesh began a broad effort on Wednesday to compile a list of young men who have disappeared and may have been recruited by militant groups for terrorist operations like last week’s massacre of 22 people at a restaurant in the capital, Dhaka.”

Some of the gunmen who stormed the cafe on July 1 were killed and at least one captured.

Reuters reports, “Confusion over exactly how many gunmen were involved was at least partly cleared up on Tuesday, when police named Saiful Islam Chowkidar, a pizza maker at the Holey Artisan Bakery, as among the six people security forces killed.”

Security forces mistakenly killed Chowkidar, assuming he was one of the attackers.

Five Bangladeshi men have been identified as the assailants who stormed the cafe: Nibras Islam, Rohan Imtiaz, Meer Saameh Mubasheer, Khairul Islam, and Shafiqul Islam, reports Reuters, noting that “several other people have been arrested.”

The pizza maker, Islam, may not be affiliated with the attackers, police have indicated, adding that his death is still being investigated.