The Israeli army said on Tuesday that it had attacked rocket launch pads in the south of Gaza during the night following rocket fire from the war-ravaged coastal strip.
In order to avoid civilian casualties, residents of eastern neighbourhoods of the city of Khan Younis were asked to leave the affected area, the army said.
Eyewitnesses said thousands of people fled to supposed safe zones further west, but these were already overcrowded.
According to Palestinian reports, at least 31 people were killed in the latest Israeli attacks in Gaza.
Seventeen Palestinians died in the city of Gaza alone, Hamas-controlled medical sources said as Israeli forces continued their operations.
According to the sources, eight more people were killed in attacks in the south of Gaza.
The information could not initially be independently verified. When asked, Israel's army said it was checking the reports.
An estimated 1.7 million Palestinians, around 85% of the population in the Gaza Strip, has been displaced in the wake of Israel's offensive since last October.
At least 37,765 Palestinians have been killed and another 86,429 injured in Gaza since then, according to its health authorities.
The war began after the attacks of October 7, when gunmen from Hamas and other militants killed more than 1,200 people in southern Israeli communities.
Around 20 rockets had been fired at Israel from Gaza on Monday, the Israeli army said. No casualties were reported. Some of the rockets were said to have been intercepted by missile defences, while others hit open ground. Hamas said it fired the rockets.
There was an air alert in towns near the border with Gaza and people had to rush to shelters.
The Israeli army once again accused Hamas of systematically violating international law and using civilian infrastructure as cover for weapons.
The military repeatedly reports that there are rocket launching pads in residential areas, weapons depots in schools and tunnels for fighters under hospitals.
Israeli ground troops continue to be deployed with support from the air in Shejaiya, a residential area in the east of Gaza City, as well as in the centre of the strip and south in the city of Rafah.
According to the army, fighting also continued in other parts of Gaza. Officials reported the deaths of two soldiers in an operation, while another was seriously injured.
