Israel bombs Gaza City in 2nd day of strikes since breaking cease-fire

Israel bombed Gaza for the second straight day Thursday as a cease-fire signed last month appeared to be falling apart between the two sides.

The Israeli government said it targeted Hamas sites in Gaza City and Khan Younis late Thursday. Explosions could be seen in the night sky from the jet strikes.

"Over the past day, arson balloons were launched from the Gaza Strip into Israeli territory," the IDF said in a statement. "In response, a short while ago, IDF fighter jets struck military compounds and a rocket launch site belonging to the Hamas terror organization in Gaza city and Khan Yunis."

The IDF went on to say it was ready for a "resumption of hostilities" if the attacks from Gaza continued.

"Earlier this evening, the IDF Chief of the General Staff held a situational assessment in which he instructed to increase the IDF's readiness and preparedness for a variety of scenarios including a resumption of hostilities, in the face of continuing terror activities from the Gaza Strip," the IDF said in the statement.

Sirens were also reported to have sounded in Kfar Aza, a kibbutz in southern Israel, just 3 miles from the Gaza border. The IDF said the sirens were triggered by "incoming fire, not rockets, from the Gaza Strip towards Israeli territory."

Israel said it struck Hamas sites in Khan Younis and the Gaza Brigades on Wednesday.

Open hostilities boiled over into airstrikes and rocket attacks between Israel and Hamas last month, killing at least 232 people -- including 65 children -- in the Gaza Strip, according to the Palestinian Ministry of Health. Ten people, including one soldier and a 6-year-old child, were killed in Israel by Hamas rockets, according to Magen David Adom, Israel's national emergency service.

After nearly two weeks of fighting, Israel’s security cabinet approved a cease-fire with Hamas on May 20 without any conditions.

"The chief of staff, the military echelon and the head of the Shin Bet reviewed with the ministers Israel's great achievements in the campaign, some of which were unprecedented," a statement from the office of then-Israeli Prime Minister Benjamin Netanyahu read. "The political echelon emphasizes that the reality on the ground will determine the continuation of the campaign."

Netanyahu was ousted as prime minister on Sunday after a vote by the Knesset, Israel's legislature. Naftali Bennett took over as the country's new prime minister.

ABC News' Morgan Winsor and Nasser Atta contributed to this report.