Bomb blasts tore through crowds celebrating the holy Christian holiday of Palm Sunday in two Egyptian cities, killing at least 44 worshipers and injuring scores more.
The Islamic State claimed responsibility for bombings at Coptic Christian churches in the Nile Delta city of Tanta, where at least 27 died, and hours later in the Mediterranean port city of Alexandria, where the death toll climbed to at least 17, the Interior Ministry said.
The attacks, which injured more than 100, came less than a week after Egyptian President Abdel Fattah al-Sisi visited the White House.
"So sad to hear of the terrorist attack in Egypt. U.S. strongly condemns. I have great...confidence that President Al Sisi will handle situation properly," President Trump tweeted.
Sisi ordered the armed forces to help police secure vital locations across the nation and declared a three-month state of emergency. The president also ordered three days of mourning for the victims.
The attacks came two months after the Islamic State released a video showing its militants pledging to kill Coptic Christians across Egypt. The footage included statements claiming responsibility for a December attack on a Cairo cathedral that killed 29 people.
Palm Sunday is among the holiest days on the Christian calendar, marking the triumphal entry of Jesus into Jerusalem, and churches traditionally draw big crowds. Susan Mikhail, who lives near St. George's Church in Tanta, told the Associated Press the explosion violently shook her building.
"Deacons were the first to run out of the church. Many of them had blood on their white robes," she told AP. Many of the more seriously wounded were carried out by survivors and shuttled to hospitals in private cars, she said.
Al-Ahram Arabic reported that security forces also dismantled two explosive devices at Sidi Abdel Rahim Mosque in Tanta, a city of more than 400,000 about 80 miles southeast of Alexandria. The mosque is considered among the most important in the city.
In Alexandria, the ministry said a suicide bomber had planned to use an explosive belt inside St. Mark's Cathedral, but the security force assigned to protect the cathedral stopped him. At least three police officers were killed preventing the suicide bomber from entering the cathedral, Ahram Online reported. Authorities said the Coptic pope for Alexandria, Pope Tawadros II, was inside leading the prayers but was not injured.
Egyptian state television broadcast footage from the church's security cameras that appears to show the suicide bomber outside the Alexandria cathedral. The man attempts to enter the cathedral but is directed to a metal detector. The man enters the detector briefly, then takes a step back before the screen is filled with smoke.
The Coptic Church is based on the teachings of St. Mark, the apostle who brought Christianity to Egypt in the first century, a dozen years after the death of Jesus. The religion claims to have about 15 million members among Egypt's 80 million people. Egyptian officials, however, have estimated the Coptic population is just a fraction of that.
Coptic churches are scattered across the U.S., with more than 20 in New Jersey alone. Joseph Ghabour, a deacon at St. Mark’s Coptic Orthodox Church in Jersey City, said several congregants of his church know people from the Tanta church.
"It seems this is going to be their game plan — to attack Christians during their holidays,’’ Ghabour said. “I was sad at the demented mentality of these people — that by killing innocents they are going to go to heaven, and it makes no sense to me.”
In Washington last week, Trump praised hard-line Egyptian leader Sisi for doing a "fantastic job" and solicited his help in the fight against terrorism and violent extremists. Sisi led the 2013 ouster of former president Mohamed Morsi, a Muslim Brotherhood leader who was elected to replace the deposed Hosni Mubarak. Since Morsi's removal, Egypt has been plagued by militant attacks.
The U.S. Embassy in Cairo issued a statement after Sunday's attacks expressing condolences to victims their families and loved ones.
"The United States stands firmly with the Egyptian government and people to defeat terrorism," the statement said.