Two blasts targeting Egyptian churches on Palm Sunday killed at least 37 people and wounded more than a 100, according to Health Ministry officials.
The first attack hit a church packed with worshipers in the Nile Delta town of Tanta, north of the Egyptian capital, killing at least 26 people and wounding 78 others, authorities said.
Hours later a second blast went off in front of a church in Alexandria, killing some 11 and injuring 35. A local police chief was killed in this explosion in the coastal city, the Ministry of Interior told Egyptian television.
The attacks are the latest in a series of assaults on Egypt's Christian minority, which makes up around 10 percent of the population and has been repeatedly targeted by Islamic extremists.
Local TV showed footage from inside the church in Tanta, where a large number of people gathered around what appeared to be lifeless, bloody bodies covered with papers.
Pope Francis, who is due to travel to Egypt later in April, condemned the killings and appealed to terrorists, arms manufacturers and traffickers to stop.
Grand Sheikh Ahmed el-Tayeb, head of Egypt's Al-Azhar — the leading center of learning in Sunni Islam — also condemned the violence, calling it a "despicable terrorist bombing that targeted the lives of innocents," AP reported.
No one immediately claimed the attacks, which came a week before Easter.
A local ISIS affiliate claimed a suicide bombing at a church in Cairo in December that killed around 30 people, mostly women, as well as a string of killings in the restive Sinai Peninsula that caused hundreds of Christians to flee to safer areas of the country.
Egypt has struggled to combat a wave of Islamic militancy since the 2013 military overthrow of an elected Islamist president.