At least 290 people were killed and more than 500 were injured in at least eight coordinated bombings on Easter Sunday in Sri Lanka. The U.S. State Department has issued advisories both for travelers currently in the country and those who had planned travel there.

Church Blasts, Negombo, Sri Lanka - 22 Apr 2019
Relatives light candles after burial of three victims of the same family, who died at Easter Sunday bomb blast at St. Sebastian Church in Negombo, Sri Lanka, . Easter Sunday bombings of churches, luxury hotels and other sites was Sri Lanka's deadliest violence since a devastating civil war in the South Asian island nation ended a decade ago.
| Credit: Gemunu Amarasinghe/AP/REX/Shutterstock

The New York Times reported on Monday that the attacks targeted at least three Catholic churches and three hotels popular with foreigners in the cities of Colombo, Negombo and Batticaloa. A majority of the victims were Sri Lankan, while at least 39 tourists were killed, including U.S. citizens, Vox reported.

The Sri Lankan government believes that National Thowheeth Jama’ath, a local radical Islamist group, is responsible for the bombings and were assisted by international militants. At least six suicide bombers carried out the attacks and officials have arrested 24 people who they believe to be connected to the bombings, reported The New York Times. No group has claimed responsibility.

In response to the attacks, the government has instituted a dusk-to-dawn curfew for the second consecutive night across the island. Social media, including Facebook and WhatsApp, has been blocked by the government in a reported effort to stop the spread of misinformation. Tuesday will be a national day of mourning and all schools will be closed until Wednesday, according to CNN.

In the meantime, Sri Lankan authorities have declared a state of emergency as they continue investigations and organize search and rescue operations. On Monday, authorities found 87 detonators at the Central Bus Stand in Colombo and performed a controlled detonation of a van parked near St. Anthony’s church, one of Sunday’s targets, reported CNN. After the initial blasts on Sunday, a pipe bomb was found on the road leading to the country’s Bandaranaike International Airport.

Multiple Bomb Blasts On Easter Sunday In Sri Lanka
Onlookers at the site of the bomb explosion at St. Anthony's Church in Colombo, Sri Lanka, on April 21, 2019. - A series of eight devastating bomb blasts ripped through high-end hotels and churches holding Easter services in Sri Lanka on April 21, killing at least 207 people, including dozens of foreigners.
| Credit: NurPhoto/Getty Images

The first confirmed U.S. citizen to be killed in the attacks was Dieter Kowalski, who was on a business trip. CNN reports that Kowalski was from Colorado and worked for Pearson, an education publishing company. His hotel was one of the targets.

“Dieter had just arrived at his hotel, where many of our colleagues have stayed over the years, when he was killed in an explosion,” Pearson CEO John Fallon said in a statement. “Colleagues who knew Dieter well talk about how much fun he was to be around, how big-hearted and full-spirited he was.”

The U.S. State Department has raised the Sri Lanka travel advisory level to “exercise increased caution” — the second-lowest of four levels — but also warned that terrorist groups “continue plotting possible attacks in Sri Lanka.”

The warning identifies areas that could be targeted, including tourist spots, malls, places of worship, public transportation areas, markets, government offices and hotels.

Travelers already in the island nation should avoid these areas, while those with planned travel to Sri Lanka should check back with the State Department for updated information on the Sri Lanka travel advisory and register their trip with the Smart Traveler Enrollment Program to receive “safety conditions in your destination country, helping you make informed decisions about your travel plans.”