Nine explosions devastated Sri Lankan churches and hotels on Easter Sunday.

Militant group ISIS claimed on Tuesday responsibility for nine catastrophic bombings in Sri Lanka on Easter Sunday, according to CBS News. Sir Lankan officials said the attacks could be retaliation for the March 15 shootings at two New Zealand mosques. At least 40 people have been arrested in connection with the Sri Lanka bombings.

As of Tuesday, a national day of mourning for the country, the death toll had climbed to 321, with hundreds wounded after bombings targeted Christian churches and hotels in three cities. In the wake of the tragedy, Sri Lanka has temporarily shut down social media access.

US citizens were among the deceased, according to Secretary of State Mike Pompeo. Japan also confirmed that one of its citizens died and four were wounded during the attack.

Bombs exploded in churches in Negombo, Batticaloa and the capital of Colombo at 8:45 a.m. local time, according to officials. The hotels hit include the Shangri-La, the Cinnamon Grand, the Tropical Inn and the Kingsbury. A housing complex in Dematagoda was also bombed.

Here are a few ways you can help those affected by the bombings in Sri Lanka. Just be wary of any group or person asking for money.

A search for "Sri Lanka" on GoFundMe shows there are at least a dozen campaigns seeking donations, including one that has already raised $28,000. However, none of the campaigns seems to be vetted, so donate with caution. 

American Red Cross is referring to the Sri Lanka Red Cross and the Asia Pacific office of the Red Cross and Red Crescent to help in the aftermath, according to a tweet on Sunday.   

If you live in Sri Lanka, you can donate blood at your local hospital through the Sri Lanka National Blood Transfusion Service. The India Times reported that hospitals are seeking blood donations and people are lining up. Social media is also driving the effort to get donations. Here's how to find your closest donation site.

If you have the means, you can travel to Sri Lanka to help those in need. The organization Volunteer Sri Lanka sends international volunteers to teach at schools, care for the elderly, help at hospitals and aid in rebuilding efforts. 

Originally published April 22.Update, April 23: Includes more details.

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