COLOMBO, April 22 (Xinhua) -- The death toll from the multiple explosions which shook Sri Lanka on Sunday had risen to 290, with over 500 being injured, the police said Monday.

In addition, 32 foreigners from the United States, Britain, Belgium and China were among those killed, according to local authorities.

The death toll was expected to rise in coming days.

Police spokesman Ruwan Gunasekera said on Monday 24 people had been arrested, though no group had yet claimed responsibility for what the authorities described as terrorist attacks.

Sunday's blasts were the worst acts of violence since the country's 30-year civil war between government troops and the Tamil Tiger rebels ended in 2009.

At least eight blasts -- mostly in or around the capital city of Colombo -- were reported during the day, with six blasts striking in the morning and two in the afternoon.

Two explosions reportedly rocked St. Anthony's Church in Kochchikade in Colombo, and St. Sebastian's Church in Negombo, north of the capital on Sunday morning, while a third one was reported to hit a church in the eastern town of Batticaloa.

Panic-stricken people were seen standing outside St. Sebastian's Church. The explosion ripped off the roof and knocked out the doors and windows at St. Sebastian's with broken glass strewn on the street.

Following the church blasts, explosions ripped through three five-star hotels in the capital.

The seventh explosion happened opposite the Dehiwala Zoo in Colombo, and the eighth struck moments later. Most of the attacks were caused by suicide bombers, State Minister of Defense Ruwan Wijewardene told reporters.

"The blasts remind me of our civil war. I hope the government could find out the cause of the explosions as soon as possible, and prevent such bloodshed from happening again," Kolitha, a local in his 50s, told Xinhua outside St. Anthony's Church.

As the South Asian island nation was reeling from the horror and loss, world leaders had expressed their solidarity and condemned the attacks.

Chinese President Xi Jinping and Premier Li Keqiang on Sunday sent condolence messages to their Sri Lankan counterparts, respectively, after multiple deadly attacks shook the country.

In his message to Sri Lankan President Maithripala Sirisena, Xi said that he was shocked to know the series of explosions in Sri Lanka, which have caused large casualties.

"I, on behalf of the Chinese government and people, as well as myself, send my deep condolences to the victims, and my sincere sympathy to the injured and families of the victims," he added.

The Chinese government and people will firmly stand by the people of Sri Lanka and firmly support the Sri Lankan government's effort to maintain national security and stability, Xi said.

On the same day, Chinese Premier Li Keqiang also sent condolences to Sri Lankan Prime Minister Ranil Wickremesinghe over the attacks.

In a statement, United Nations Secretary-General Antonio Guterres expressed his deepest condolences and wished a speedy recovery to the injured.

Russian President Vladimir Putin on Sunday extended his condolences to Sri Lanka.

"Our country shares the grief of the victim's families and friends and hopes for a prompt recovery of those injured," Putin said in a message published on the Kremlin's website.

Jean-Claude Juncker, president of the European Commission, tweeted: "It was with horror and sadness that I heard of the bombings in #SriLanka costing the lives of so many people. I offer my heartfelt condolences to the families of the victims who had gathered to worship peacefully or come to visit this beautiful country. We stand ready to support."

Donald Tusk, president of the European Council, wrote on his Twitter account: "A tragic Easter in Sri Lanka. My thoughts are with the families of those killed in the attacks on churches and hotels; and those still fighting for their lives."

In his early morning tweet on Sunday, U.S. President Donald Trump called the incidents "a terrorist attack." He said that "the United States offers heartfelt condolences to the great people of Sri Lanka.

Britain, Germany, France, Pakistan, Israel, Saudi Arabia, Turkey among other countries also joined the international community in condemning the multiple blasts.