The Ashdod municipality on Monday morning canceled classes in all schools that aren’t fortified against rockets, fearing an escalation in attacks on the southern city a day after the Israeli Air Force targeted a terror suspect in the Gaza Strip.

The decision meant some 4,000 students stayed home.

Three Palestinians were injured when an IAF aircraft struck a motorcycle in Jabaliya in the northern Gaza Strip on Sunday morning. The IDF said that the target, Ahmed Sa’ad, who was riding the motorcycle, was suspected of firing rockets at Israel. Sa’ad was critically injured in the strike, a Palestinian health official said.

Sa’ad, 22, “was a key Palestinian Islamic Jihad operative in the Gaza Strip specializing in rocket launching,” the army said in a statement. He was “personally responsible” for a recent series of rocket attacks against Israel, and his “terrorist activities over the years include concealing, directing, and launching rockets at southern Israel in numerous incidents,” the statement read.

The attack came after Israeli planes hit two sites in the Gaza Strip in retaliation for an earlier rocket strike at southern Israel. The Israeli Air Force hit two “terror sites” in the southern and central Strip, according to a statement from the IDF Spokesperson’s Unit early Sunday morning.

Ashdod Mayor Yehiel Lasri announced on Sunday afternoon that classes in some schools would be canceled Monday “in light of the continuing escalation and following a situation assessment in the city.”

A similar decision was made on Friday due to rocket fire from the Strip.

The school closures did not affect the majority of Ashdod’s schoolchildren, who number about 54,000. Most of the unprotected schools in Ashdod are in ultra-Orthodox neighborhoods.

Southern Israeli cities in proximity to Gaza were the targets of constant rocket fire for years before Operation Pillar of Defense in November 2012. Rocket fire from the Strip tapered dramatically following the eight-day Israeli military campaign, though there have since been sporadic attacks.

Israeli officials have vowed to respond forcefully to attacks out of Gaza.

Joshua Davidovich and AP contributed to this report.