At least one Palestinian was killed and two Israelis were injured Thursday amid escalating violence between Israel's military and militants in the Gaza Strip.
The clashes marked the first time the Israel Defense Forces successfully deployed a new short-range rocket interception system, Iron Dome, to destroy a Palestinian rocket launched toward the city of Ashkelon.
Tensions have been rising following Israel's killing last weekend of three Palestinian militants, including a senior commander for Hamas, the Islamist group that controls Gaza. Israeli officials said the men were plotting a terrorist attack in the Sinai peninsula.
On Tuesday, two other Hamas leaders were reportedly killed while driving in northern Sudan. Sudanese government officials accused Israel of launching an airstrike against their vehicle. Israeli officials declined to comment, but they have previously complained about arms-smuggling convoys operating in Sudan, which they say provide weapons to Gaza.
Hamas officials, who had previously called for a cease-fire with Israel, vowed to retaliate.
On Thursday, militants fired an antitank missile that hit a school bus in southern Israel, near the Gaza border, critically wounding a 16-year-old boy and the bus driver.
"Terror has chosen to up things a notch with an intolerable and barbaric attack on a yellow [school] bus," Alon Schuster, head of the local council for the area, told Israel Radio.
Israel immediately responded with airstrikes against nine targets in Gaza, killing at least one person and wounding about half a dozen others.
Militants responded by firing nearly four dozen mortar rounds and rockets, most of which landed in open spaces, Israeli military officials said.
Israeli Defense Minister Ehud Barak said in a statement that Israel would hold "Hamas responsible for all terrorist attacks emanating from the Gaza Strip."
Military officials praised the success of the Iron Dome system, which was deployed last week and is still in the testing phase. Witnesses told Israeli news media that they saw the interceptor missile knock an incoming rocket out of the sky.
But military officials expressed concern about the growing use by militants of antitank missiles, which only recently began to be employed in Gaza.