Two Palestinians have been killed in an Israeli strike in Israel’s newly declared buffer zone in the northern Gaza Strip.
The Israeli army said troops fired at a group preparing to fire rockets into Israeli territory, near Beit Lahiya.
Israel declared the area a “no-go zone” earlier this week in response to an increase in militant rocket attacks.
In a separate incident, gunmen briefly seized the United Nations club in Gaza City, but no injuries were reported.
Officials said five men tied up the club’s guard, before throwing two explosive devices, causing some damage to the building.
The club, known as the only place which served alcohol in Gaza City, was closed at the time.
The Palestinian Interior Ministry issued a statement condemning the Israeli strike, saying a shell hit a Palestinian post, hindering police efforts to stop militants from firing a rocket at Israel.
Palestinian security sources told the Reuters news agency that the two dead men – and another man who was injured – were militants.
One was said to have belonged to al-Aqsa Martyrs Brigades, which is part of Mr Abbas’ Fatah group.
One of the men was an off-duty policeman, and the three had been walking in a field near the officer’s home, the security sources said.
Frequent Palestinian militant rocket attacks and Israeli artillery fire and air strikes have marred a fragile truce Palestinian militants declared earlier in the year at the request of Palestinian leader Mahmoud Abbas.
The truce formally ended at midnight (2200 GMT).
Speaking to reporters at the Gaza hospital where the casualties were taken, Hamas spokesman Mushir al-Masri threatened revenge against Israel.
However, he did not rule out extending the truce.