Israel carried out airstrikes on the Gaza Strip early Wednesday after militants in the Palestinian territory sent incendiary balloons into the south of the country, in the first flare-up between the two sides since a major conflict in May in which hundreds were killed.
According to Palestinian sources, Israel's air force targeted at least one site east of Khan Yunis in the south of the Gaza Strip, which is home to some two million people.
An AFP photojournalist in Khan Yunis saw the explosions.
The Israeli army said that in response to the "arson balloons", its "fighter jets struck military compounds belonging to the Hamas terror organization".
It added that "facilities and meeting sites for terror operatives" in Khan Yunis were targeted. There was no indication of casualties so far.
The army added that it was "prepared for any scenario, including a resumption of hostilities, in the face of continuing terror activities from the Gaza Strip."
Local firefighters said the incendiary balloons caused around 20 fires in southern Israel.
The violence is the first flare-up between Israel and Palestinian militants since a ceasefire came into place in May, ending 11 days of heavy fighting that killed 260 Palestinians including some fighters, the Gaza authorities said.
In Israel, 13 people were killed, including a soldier, by rockets and missiles fired from Gaza, the police and army said.