Palestinians in Gaza fired dozens of rockets at southern Israel on Monday, critically wounding one person in a strike on a bus, medical officials said, a day after an Israeli incursion prompted deadly fighting in the enclave.
Smoke billowed from the bus and Israeli interceptor missiles streaked through the sky as sirens sounded in Israeli communities near the Gaza border.
Israel's military said more than 80 rockets were launched from Gaza and it was conducting retaliatory air strikes for the fire it blamed on Hamas.
The frontier had been quiet earlier in the day after a botched Israeli undercover operation in the Gaza Strip led to fighting that killed a Hamas commander, six other Palestinian militants and an Israeli colonel.
"In response to yesterday's crime, the joint command of Palestinian factions announce the beginning of bombardment of the enemy's settlements with scores of rockets," Hamas's armed wing said in a statement after funerals were held for the militants.
Late on Sunday, Palestinians fired 17 rockets into southern Israel in response to the Israeli incursion and air strikes, which Hamas, the dominant Palestinian armed force in the Gaza Strip, said were intended to cover the retreat of a car used by the Israeli troops.
There were no reports of injuries or damage in Israel in the incidents on Sunday, but the military said a lieutenant-colonel, identified only as "M", had been killed in the raid and another officer wounded.
Hamas said the Israeli actions dealt a blow to Egyptian, Qatari and UN efforts to broker a long-term ceasefire and ease an Israeli blockade that has deepened economic hardship in Gaza.
Israel and Hamas have fought three wars — the latest in 2014 — since the group seized the Gaza Strip from forces loyal to Palestinian President Mahmoud Abbas in 2007.
Violence has flared regularly along the Israel-Gaza border since Palestinians began protests on March 30 to demand rights to land lost to Israel in the 1948 war of its creation.
Israeli gunfire has killed more than 220 Palestinians since the start of the demonstrations, which have included breaches of Israel's border fence.
Hamas said that during Sunday's fighting, assailants in a passing vehicle opened fire on a group of its armed men, killing one of its local commanders, Nour Baraka.
A pursuit ensued and witnesses said an Israeli aircraft fired more than 40 missiles into the area. Palestinian officials said that in addition to Baraka, five other Hamas men and a member of the Popular Resistance Committees were killed.
In an apparent attempt to defuse tensions, Israel's chief military spokesman said the special forces had not been dispatched to assassinate Hamas commanders, a tactic that led to wider conflict in the past and which has largely been abandoned.
The spokesman, Brigadier-General Ronen Manelis, told Army Radio that covert missions were mounted frequently, suggesting that Israeli forces may have been gathering intelligence.
Israeli Prime Minister Benjamin Netanyahu cut short a visit to Paris, where he attended World War I commemorations with other world leaders. He returned home early on Monday.