Israeli fire killed at least two people in Rafah and injured three others in Khan Younis in the south of Gaza, raising fear among Palestinians that the ceasefire could collapse altogether after Israel imposed a total blockade on the shattered enclave.
A first phase of a ceasefire between Israel and Palestinian militant group Hamas that began in January ended over the weekend with no agreement on what will happen next.
Hamas says an agreed second phase must now begin, leading to a permanent Israeli withdrawal and an end to the war. Israel has instead offered a temporary extension into April, with Hamas to release more hostages in return for Palestinian detainees, without immediate talks on Gaza's future.
According to Reuters, two Israeli government officials said mediators had asked Israel for a few more days to resolve the standoff.
Israel raised the stakes on Sunday by imposing a total blockade on all supplies, including food and fuel, to sustain the 2.3 million Gazans living among the ruins after the 15-month conflict.
Hundreds of lorries carrying supplies were backed up in Egypt, denied permission to enter.
Residents said Israeli tanks stationed near the eastern and southern borders of Gaza intensified gunfire and tank shelling into the outskirts throughout the night, raising fears among the population that fighting could resume.
A Palestinian official with a group allied to Hamas told Reuters a state of alert had been declared among fighters.
At least two people were killed by an Israeli drone fire in Rafah, and three people were wounded by a helicopter that fired on Khan Younis, medics said.
In a statement, the Israeli military said its forces fired at a motorboat in the coastal area of Khan Younis, violating security restrictions in the area and posing a threat.
The military said in another incident in southern Gaza, its forces identified two suspects who were moving towards them and posing a threat. Israeli forces "fired at the suspects to eliminate the threat and identified casualties," it said.
