Israeli planes on Thursday hit targets in the northern Gaza Strip effectively ending an undeclared truce that led to a drop in violence, the Israeli armed forces announced.
Israel's attack came after a dozen rockets were fired towards southern Israel from the Gaza Strip, with the projectiles causing no harm.
"The Israeli air force raid targeted a rocket launch that was ready to fire in the Beit Hanun area in the northern Gaza Strip," an Israeli army spokesman told AFP.
"Twelve rockets were fired from Gaza towards southern Israel overnight," he added. "Two of the rockets exploded at Sderot, damaging a building, but without injuring anybody."
Palestinian hospital officials said no one was hurt in the Beit Hanoun air raid.
Israel and the Palestinians had respected a tacit truce since March 8 which led to a drop in violence.
Israeli undercover agents on Wednesday killed four Palestinian militants, including two senior leaders of the radical Islamic Jihad, in the West Bank town of Bethlehem.
The West Bank dead included Mohammed Shahada, 48, a top leader in the armed wing of the Islamic Jihad movement, and Ahmed al-Balbul, 48, a senior official in the Al-Aqsa Martyrs Brigades, an armed group loosely tied to Palestinian president Mahmoud Abbas's Fatah party, Palestinian security officials said.
The other two men were identified as Imad al-Kamel and Eissa Marzuk, both militants in Islamic Jihad.
At least 351 people have been killed since Israel and the Palestinians formally relaunched peace talks at a U.S. conference in late November, according to an AFP count.