JERUSALEM — Two Palestinians were killed in an Israeli airstrike and four Israelis were wounded by mortar fire from Gaza on Saturday as fighting in and around the Gaza Strip escalated to what the Israeli prime minister called the most intense level since the 2014 war.

Hamas and allied Islamic militant groups fired nearly 100 projectiles at Israeli territory throughout the day, most of them mortar rounds, though rockets were fired at the city of Ashkelon.

Israel’s Iron Dome air-defense batteries intercepted more than 20 of those that had the potential to do damage, the military said, but some got through. A mortar struck the courtyard of a Sderot synagogue, according to the Israeli military, and local news media reported that a house in Sderot was also hit, wounding four members of a family.

“All the house was smoke and glass,” said one member, Aharon Buchris, from his hospital bed in Ashkelon, where he was treated for head and leg wounds. His wife and two daughters were also hurt. “There was a lot of blood. The television exploded, the aquarium exploded.”