Sri Lankan authorities on Sunday arrested eight citizens for the bombings that killed more than 200 people and described the attacks as a terrorist act by extremist groups, while international reactions to the attacks continue.

Sri Lankan Prime Minister Ranil Wickremesinghe said security forces had arrested eight people most likely to be linked to the blasts, adding that they were Sri Lankans and that investigations were now going on to see whether they were linked to outsiders.

He said his government had "received information about a possible attack but insufficient precautions had been taken to prevent it" and that the police would issue a statement on the persons responsible for the attack after the investigation was completed.

For his part, the Sri Lankan defense minister described the attacks as "terrorist acts by extremist groups" without giving further details.

Part of the vandalism of the Church of Saint Sebastian in the attack (Anatolia)

Hundreds of victims
Sri Lanka today has killed at least 218 people, including 35 foreigners, some from the United States, Denmark, China, Japan, Pakistan, Morocco, India and Bangladesh, and some 450 injured.

US Secretary of State Mike Pompeo said in a statement that the United States government could confirm the presence of several Americans among the victims, without specifying a specific number, adding that his country's embassy in Colombo was working to help the affected Americans and their families.

The authorities imposed tight security and a 12-hour curfew, as of this evening; it also announced the blocking of major social networking sites and messaging services in the country.

The attacks on churches and hotels coincided with the Christian revival of Easter, when Pope Benedict condemned the attacks. "I would like to express my sympathies to the Christian community that was attacked during his prayer and to all the victims of such cruel violence," he said during the Easter Mass.

Ambulance injured from targeted church (Reuters)

Wave denunciation
The blasts launched a wave of denunciations from world leaders and officials, with Russian President Vladimir Putin hoping to punish those responsible for the bombings. He said Russia was and remains a reliable partner of Sri Lanka in the fight against international terrorism.

Australian Prime Minister Scott Morrison also said he condemned what he described as the horrific attacks on innocent people in churches and hotels in Sri Lanka.

UN Secretary-General Antonio Guterich expressed concern about the attacks and called in a press release to sanctify places of worship around the world and bring the perpetrators to justice as soon as possible.

Earlier, other leaders condemned the attacks and called for tougher anti-terrorism efforts, including US President Donald Trump, German Chancellor Angela Merkel, British Prime Minister Theresa May, French President Emmanuel Macaron and European Commission President Jean-Claude Juncker.

Turkish President Recep Tayyip Erdogan also condemned the attacks, calling for combating terrorism of all kinds, while the Turkish Foreign Ministry considered that the attacks are no different from the killing of worshipers in New Zealand.

Qatar's emir, Sheikh Tamim bin Hamad al-Thani, said in a statement that "he strongly condemns this heinous crime," while the Qatari foreign minister stressed Qatar's total refusal to target places of worship and intimidate the safe.