Bombs ripped through Christian churches and tourist locations in Sri Lanka on Easter Sunday, killing at least 290, including two Americans. The government blamed a known Islamist extremist group, a conclusion that made more sense when they admitted that they had been warned weeks earlier that an attack was coming. ABC News reports that the bombings took place over the entire day, consisting of “coordinated” suicide attacks by the extremists, but that the police have made some arrests:

Sri Lanka on Monday accused a local Islamist extremist group, the National Thowheed Jamaath, of being behind a string of Easter bombings against churches and hotels that killed at least 290 people.

Health Minister Rajitha Senaratne said the group, which roughly translates as National Monotheism Organization, perpetrated the attack using suicide bombers against three churches and three hotels, adding that it likely had international links.

“We do not believe these attacks were carried out by a group of people who were confined to this country,” he said. “There was an international network without which these attacks could not have succeeded.”

He also called for the police inspector general, Pujith Jayasundara, to resign because security agencies had received a report warning of attacks by this group against churches and hotels weeks before.

The Washington Post got a copy of the intelligence report warning of “potential suicide attacks” by the NTJ, which identified its leader as  Mohamed Zaharan. No one is quite sure yet why police didn’t act on the intelligence when it was received, but it’s certain to be a very big topic of converstion in Sri Lanka and around the world. The government’s claim that NTJ was part of an international network may very well be true, especially after the collapse of ISIS. It might also be an excuse for a massive failure to stop what turned out to be a very successful mission of evil by these extremists even with a head start.

Reuters reports that experts think the government’s claim is credible. The Mumbai-level of coordination and length of operation does suggest a particular sophistication that indicates involvement by experienced terror networks. Oddly, though, none of them have claimed credit for the attack yet:

No group has claimed responsibility for the explosions, many of them suicide bombings, which killed 290 people and wounded 500 others – the deadliest attack in the island nation since the end of a civil war in 2009.

Experts said the targeting of churches and hotels where foreign tourists stay in Sri Lanka, which endured several suicide bombings targeting government officials and installations during the civil war, was a “new and worrying development” in the predominantly Buddhist country.

“These synchronised attacks are out of the ordinary for Sri Lanka. Compared with similar attacks in the Middle East and Southeast Asia, it has the DNA of attacks carried out by Islamic State and al Qaeda,” said Alto Labetubun, an anti-terrorism expert who has researched the two groups for a decade.

A senior Asian counter-terrorism official who declined to be identified said the attack was likely carried out by a group with “significant operational capability and skilled commanders”.

If so, why no immediate claim of credit? Perhaps it’s because the operation may not yet be over. As ABC noted, police found a suspicious van today, and CBS caught the result of their attempt to neutralize it. ABC called this a controlled demolition, but the CBS reporter isn’t so sure:

CBS News staff in the Sri Lankan capital reported a large explosion on Monday afternoon as police investigated the series of devastating suicide bomb attacks from the previous day.

Witnesses told the Reuters news agency that an explosives-laden vehicle had blown up as law enforcement officers attempted to defuse devices inside it.

Police went to inspect the van Monday after people reported it had been parked near St. Anthony’s Shrine, one of the churches in which dozens were killed by bombers, since Sunday. They discovered three bombs that they tried to defuse, but the bombs detonated, sending pedestrians fleeing in panic.

Meanwhile, police are still finding other potential threats, or at least pieces of them:

There were reports of other devices found around the city, including dozens of detonators apparently found in Colombo’s main bus station.

By late last night, the government finally appeared to be getting ahead of the terrorists, defusing a massive IED at or near their airport. The continued discovery of devices today might mean that the worst is over for this operation. However, this was the worst — perhaps the worst Islamist terror attack since Mumbai or even 9/11, with 290 dead and more than 500 injured. It’s a horror that will not be soon forgotten — and it serves as a harsh reminder that Islamist terror networks still represent a unique and lethal threat.