In retaliation for incendiary balloons launched from Gaza, Israel claims to have undertaken air attacks on Hamas targets.
In the early hours of Wednesday, Gaza City was rocked by explosions.
According to the Israeli fire department, many balloons were launched from Gaza into Israel early on Tuesday, triggering numerous fires.
It's the first big flare-up since the two sides agreed to a truce on May 21 after 11 days of combat.
It came after a Jewish nationalist march in occupied East Jerusalem on Tuesday, which drew threats from Hamas, the Gaza-based terrorist group.
The Israel Defense Forces (IDF) stated in a statement that its fighter planes had struck Hamas military installations in Khan Yunis and Gaza City.
The IDF was "prepared for all eventualities, including the restart of hostilities, in the face of continuous terror actions from the Gaza Strip," it stated, adding that "terrorist activities" had taken place in the facility.
It's unclear if the air attacks resulted in any injuries.
Palestinians will continue to pursue their "brave resistance and protect their rights and sacred places" in Jerusalem, according to a Hamas official who issued a statement on Twitter.
The incendiary balloons fired earlier from Gaza ignited at least 20 fires in fields in southern Israel, according to Israel's fire department.
This is the first violent incident since Israel's new coalition government, led by Naftali Bennett, took office last weekend, ending Prime Minister Benjamin Netanyahu's 12-year reign.
After weeks of growing tension in East Jerusalem, which culminated in confrontations at al-Aqsa, a holy site venerated by both Muslims and Jews, fighting between Israel and Palestinian militants in Gaza began on 10 May. Hamas requested that Israel evacuate police from the area as well as Sheikh Jarrah, a largely Arab neighborhood adjacent where Palestinian residents are facing displacement by Jewish settlers.
After telling Israel to leave the position, Hamas began launching missiles, prompting retaliatory airstrikes.
The Israeli military claims that terrorists launched over 4,300 rockets into its territory and that it attacked over 1,000 terrorist positions in Gaza.
Egypt and other nations later mediated a ceasefire, which took effect on May 21.
According to Gaza's health ministry, at least 243 individuals were murdered in Gaza during the fighting, including more than 100 women and children. Israel has claimed responsibility for the deaths of at least 225 Palestinian terrorists.
According to Israel's medical service, 12 persons were murdered, including two children.