"We have just witnessed in the past week the largest displacement of Palestinians since 1948. People are forced to migrate in masses before our eyes, and while some recall their traumas in the past, others witness the traumas of their ancestors," she said in reference to the Nakba, or mass displacement of Palestinians from what is now Israel during the 1948 war.
Touma said around 800,000 people had taken refuge in UNRWA facilities in the Gaza Strip.
"The northern, southern and central regions of Gaza are not safe. There is no safe place in Gaza, and 103 United Nations employees who had nothing to do with this conflict lost their lives," she added.
"These were our colleagues, civil servants of the UN dedicated to serving their community. They are dead now."
Israel has launched relentless air and ground attacks on the Gaza Strip since a cross-border attack by the Palestinian resistance group Hamas on Oct. 7.
At least 11,500 Palestinians have since been killed, including more than 7,800 women and children, and more than 29,200 injured, according to the latest figures from Palestinian authorities.
Thousands of buildings, including hospitals, mosques and churches, have also been damaged or destroyed.
The Israeli death toll, meanwhile, is around 1,200, according to official figures.
