Palestinians in Gaza fired scores of rockets, mortar bombs and at least one anti-tank missile into southern Israel on Monday while Israel launched retaliatory air strikes.

The exchanges came a day after an Israeli incursion prompted deadly fighting in the enclave.

Three Palestinian gunmen were killed in the air attacks, their factions said.

On the Israeli side of the border, a guided missile destroyed a bus, critically wounding a soldier, and shelling struck at least two homes, authorities said.

The flare-up cast a new cloud over efforts by Egypt, Qatar and the United Nations to broker a long-term ceasefire between Israel and Hamas, the dominant Islamist group in Gaza.

The enemies have fought three wars in the past decade.

On Sunday, Israeli Prime Minister Benjamin Netanyahu said he hoped to reach an “arrangement” to avoid another conflict and ease Israeli-blockaded Gaza’s economic hardships.

The U.S. , whose attempt to seal a wider Israeli-Palestinian peace stalled in 2014, condemned Hamas.

“We stand with Israel as it defends itself against these attacks,” U.S. envoy Jason Greenblatt tweeted.

“This violence prevents any real help for the people of Gaza.”

In southern Israel, interceptor missiles streaked through the sky and sirens sounded during what the military said were more than 200 rocket and mortar launches from Gaza.

Israeli medics said at least 10 people were hurt. In Gaza, medics said three people were wounded and a university building was damaged.

The frontier had been quiet earlier in the day after a botched Israeli undercover operation in Gaza 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 said in a statement after funerals were held for the militants.

Late on Sunday, Palestinians fired 17 rockets into Israel in response to the Israeli incursion and air strikes, which Hamas said were intended to cover the retreat of a car used by the Israeli commandos.

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.

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, killing local commander Nour Baraka, five other members and a Popular Resistance Committees gunman.

In an apparent attempt to defuse tensions, Israel’s military spokesman said the special forces had not been dispatched to assassinate Hamas commanders.

Such  a tactic had led to wider conflict in the past and which has largely been abandoned.

Israeli media reports suggested the raid was mounted to gather intelligence. (Reuters/NAN)