The Hamas militant group targeted Tel Aviv with dozens of rockets on Tuesday evening after Israel stepped up the intensity of its air strikes on the Gaza Strip, threatening to turn a two-day round of hostilities into a broader conflict.

Flights were rerouted as the skies over central Tel Aviv were lit up with Israel’s Iron Dome defences tracking dozens of rockets simultaneously. One hit a reportedly empty bus in Holon to the south of Tel Aviv. At least six people received medical attention and more casualties are expected.

The escalation came hours after prime minister Benjamin Netanyahu ordered a broadening of Israel’s air campaign in the Gaza Strip, as the Israeli military sought to degrade Hamas’ operational abilities with dozens of bombing runs, targeting rocket launching pads and military commanders.

“Hamas will receive blows here that it did not expect,” Netanyahu said on Tuesday evening. Hamas responded with a vow to attack Tel Aviv, saying it had launched 130 rockets at a time, probably a tactical attempt to overwhelm the Israeli air defences.

Defence minister Benny Gantz, who has ordered 5,000 reserve troops back to duty, said earlier that Israel’s air strikes would continue until “its operational goals are met”.

Palestinians evacuate a building targeted by an Israeli bombardment in Gaza City

Authorities in Gaza say 24 Palestinians have been killed, including nine children, although it is not clear if all the deaths were owing to Israeli air strikes. Israel had killed at least 20 Hamas and Palestinian Islamic Jihad militants, according to the Israel Defense Forces. With Israel carrying out complex manoeuvres, it warned that civilian casualties were likely. “Some of the firing pits are embedded within the civilian population and it cannot be ruled out that there will be civilian casualties,” it said.

After days of tension inside Jerusalem, the militant group that runs Gaza fired rockets towards the city, the furthest into Israel since 2014, on Monday night. Israel responded immediately with dozens of targeted air strikes.

The Hamas action came after Israeli police on Monday cleared Jerusalem’s al-Aqsa mosque, a holy site for Muslims and Jews, injuring hundreds of Muslim protesters with tear gas, stun grenades and rubber bullets. Palestinians have been angered by restrictions near the mosque and the planned evictions of Arabs to make way for Jewish settlers.

Egyptian, Qatari and UN officials who mediate between Israel and Hamas were trying to restore calm, an Israeli official said on Tuesday. Israel had rejected Hamas’s first offer of a truce, Channel 12 TV reported.

The Arab League described Israel’s response in Gaza as “indiscriminate and irresponsible” and “a miserable show of force at the expense of children’s blood”.

White House spokesperson Jen Psaki said President Joe Biden had been receiving updates from his national security team and that his primary focus was on de-escalation.

She said the US condemned rocket attacks by Hamas and other groups, including attacks on Jerusalem, and that Biden’s support for “Israel’s security, for its legitimate right to defend itself and its people, is fundamental and will never waver”.

“Jerusalem, a city of such importance to people of faith around the world, must be a place of co-existence,” Psaki said.

The UN Security Council would meet in private session on Wednesday, diplomats said, to discuss the outbreak of violence.

In a sign of widening unrest, riots have broken out in several Israeli towns including Lod, Ramle and Jaffa. There were also clashes in Hebron in the West Bank. “There were wild disturbances here yesterday, which we cannot tolerate, by young hotheads. Our directive is to do everything to maintain law and order,” said Netanyahu.

As well as the two deaths, six Israelis have been injured in the rocket attacks, according to Israeli medics. Two rockets hit a house and a multistorey apartment building in Ashkelon, a city near the Gaza Strip, according to a separate report on Kan Radio on Tuesday. It said 30 people were being treated at a nearby hospital.

Tensions had risen as a court case regarding the evictions coincided with an annual Israeli celebration that began on Sunday called Jerusalem Day, when Israelis celebrate their conquest of Arab East Jerusalem in 1967. The hearing has been postponed.

The violence comes at a precarious time in Israeli politics. Netanyahu’s position has been weakened as coalition talks progress between his rivals, who are close to securing a government that could dethrone the five-time premier. His rightwing supporters view the evictions in East Jerusalem as an important part of a long-running strategy to replace Arabs with Jews in the Holy City.

Additional reporting by Heba Saleh in Cairo