In the past 72 hours, more than 38,000 Gazans have had to flee their homes and seek shelter inside schools run by the UN.
Israel has launched a powerful air assault on Gaza, which is considered to be one of the most densely populated areas in the world.
The Israeli military says it is aiming at Hamas militants and installations but to date at least 192 people have been killed in Gaza, including 58 children and 34 women.
The Israeli death toll stood at 10 yesterday, including a boy, 5, and a soldier.
The heaviest round of fighting since the 2014 conflict between Israel and Hamas has left civilians traumatised.
“Last night was the worst night in terms of military fighting,” said Matthias Schmale, Gaza operations director of the UN agency for Palestinian refugees.
"We had at 2am, I think, 11 or 12 massive hits in the surrounding area and it’s frightening, it’s terrifying. For civilians it's terrifying.”
The shelling has become so intense that more than 38,000 people have fled their homes.
"People just started packing up and leaving their homes out of fear," Mr Schmale told The National from the UNRWA's offices in Gaza.
While the UN said it is equipped to handle up to 100,000 people at 50 schools spread out across Gaza, it is concerned that the cramped conditions could lead to another surge in Covid-19 cases.
Gaza was on the end of a second wave, which had killed 400 people in March and April, when this latest round of violence started.
“We have thousands of unvaccinated people together in not big spaces,” Mr Schmale said.
“In Covid terms we are racing against time to try to make sure that we at least separate people with symptoms from those who don't, and we provide PPE.”
The fighting has also stopped the UN’s vaccination work in Gaza. “For the last week our vaccination programme has been at a standstill,” he said.
Mr Schmale said that the halt in inoculations could make it harder to prevent a third wave of the virus.
“People will be less resilient because we just won't have the numbers in terms of vaccinated people.”
He said that if the fighting continued for much longer, there was a strong possibility of a rapid rise in Covid-19 cases, compounding an already difficult situation.