Israeli forces have continued to hit targets across the Gaza Strip, just hours after a ceasefire was reported to have taken effect.
The ceasefire was brokered by Egypt on Monday but shortly afterwards there were air raid sirens heard in southern Israel and rocket fire reported from Gaza.
At least 30 rockets were fired into Israel on Monday, according to Israel, but nearly all of them were intercepted or landed in uninhabited areas.
But six Israelis were injured when a rocket landed on a home in a farming community.
The Iron Dome rocket defence system had not been activated because the attack was unexpected.
In retaliation, Israel hit back with 15 airstrikes in the Gaza Strip on Tuesday, including the offices of Hamas’s supreme leader Ismail Haniyeh.
The building was destroyed, as was another in Gaza City that Israelis identified as the militant group’s military intelligence headquarters.
Seven Palestinians were injured but none were killed, according to Gaza’s health ministry.
Commenting on the rockets fired into Israel, the country’s prime minister Benjamin Netanyahu said: “Israel will not tolerate this. I will not tolerate this.”
Speaking during a meeting at the White House with US President Donald Trump, he added: “Israel is responding forcefully to this wanton aggression.
“We will do whatever we must do to defend our people and defend our state.”
The renewed violence comes as Mr Netanyahu faces a tough race for re-election on 9 April, with critics accusing him of being too soft on Hamas.
He has been indirectly involved in the ceasefire talks through Egyptian mediators and he even allowed Qatari aid to be delivered to Hamas to help those in Gaza.
Hamas, meanwhile, has its own problems: the US has recently recognised Israel’s control of the Golan Heights and the Israel-Egyptian blockade, sanctions by the Palestinian Authority, and Hamas’s own incompetence have worsened the economic situation in Gaza.
More than half of those living in the strip are unemployed.
Last week hundreds of Gazans protested against the poor conditions but Hamas responded by beating and arresting dozens of them.
In a statement, Mr Haniyeh said Palestinians “will not surrender” and their militants “will deter the enemy if it exceeds the red lines”.
Israel and Hamas have fought three wars, the most recent in 2014, which lasted 50 days and killed more than 2,000 Palestinians and 73 Israelis.