EL-ARISH, Egypt - A top Syria-based Hamas leader secretly crossed into Gaza for his first visit in decades, an Egyptian security official on the border said Saturday.

Moussa Abu Marzouk entered the Gaza Strip late Thursday with three other Hamas officials before returning to Egypt the following day, the official said. He spoke on condition of anonymity because he was not authorized to speak to the press.

Hamas' leadership is divided between the Gaza Strip, which the group rules, and its top officials living in Damascus. Abu Marzouk is number two in the Hamas hierarchy. He was born in Gaza and grew up in a refugee camp in the southern part of the strip, but hasn't been back in several decades.

Hamas has been holding talks in Cairo seeking reconciliation with its Fatah rival. Both sides are working to form a unity government. The purpose of Abu Marzouk's visit remains unknown. Hamas denies he entered Gaza and Abu Marzouk's Gaza relatives say they had not seen him.

In addition to Palestinian reconciliation talks, international and regional diplomats are also currently involved in efforts to try to cement a truce between Israel and Hamas and pledge funds to help rebuild Gaza after Israel's punishing three-week-long offensive.

On Saturday, two rockets fired from Gaza crashed into southern Israel -- one into a school that was closed for the weekend in the coastal city of Ashkelonand another into an open field.

There were no Palestinian claims of responsibility for the rocket fire, which highlighted the fragility of the truce that was called separately by Israel and Hamas on Jan. 18.