Israel has heavily bombed Gaza City overnight with unconfirmed reports from the US news site Axios and the Jerusalem Post that the military has now launched its ground offensive to occupy the entire city, BBC reported.

Israeli strikes are also reported in central Gaza, in the direction in which thousands of people are fleeing. Palestinian officials say there are rising numbers of deaths and injuries.

The intensification came ahead of a long-threatened full-scale ground invasion of the city, which is home to hundreds of thousands of people. 

It came hours after Secretary of State Marco Rubio assured Israeli Prime Minister Benjamin Netanyahu of unwavering US support during a trip to Jerusalem on Monday, according to BBC.