ISMAILIA, Egypt — Egyptian Christians fearing attacks by Islamic State militants fled the volatile northern part of the Sinai Peninsula for a fourth day on Sunday, after a string of sectarian killings there sent hundreds fleeing and raised accusations the government is failing to protect the minority.

More than 100 families from the town of el-Arish and nearby have come to the Suez Canal city of Ismailia, 75 miles east of Cairo, since Friday, Nabil Shukrallah of the city’s Evangelical Church said.

Families arrive scared and in need of supplies, which are being stockpiled at the church via donations from several parishes, he said. They are then transported to be housed in and around the city, in private homes and now also accommodation provided by the government.

‘‘They’re exhausted, with urgent needs for food and children’s clothing,’’ he said, as one father carried off a sick infant to be evacuated by ambulance. ‘‘They’re terrified of the violence and brutality of the terrorists.’’

Northern Sinai has for years been the epicenter of an insurgency by Islamic militants, and the area’s few Christians have slowly been trickling out. But departures rose in earnest after suspected militants gunned down a Christian plumber at home in front of his family on Thursday in el-Arish.

It was the seventh such killing in recent weeks and stoked panic among Christians.

No militant group has claimed responsibility for the attack. But Egypt’s Islamic State affiliate, which is based in north Sinai and which in December carried out a devastating suicide bombing against a Cairo church, vowed in a video earlier this week to step up attacks against Egypt’s embattled Coptic Christian minority.