“There is damage to every part of civilian infrastructure imaginable. Water, electricity, food, shelter, everything will need aid,” said Muhammed Abu Halima, a U.N. aid worker who works at a Gaza school that has been converted into a shelter. “It will take years for Gaza to recover.”

The United Nations announced this week that it was launching a $115 million plan for reconstruction in Gaza, where homes, schools and hospitals have been destroyed.

“With every hour that goes by, the destruction in Gaza is furthered, and the U.N. will need to revise that $115 million plan upwards,” said Chris Gunness, a U.N. spokesman.

Food and water have been scarce since last week, when thousands streamed into U.N. facilities in central Gaza to escape the bombardment in the northern, southern and eastern part of the coastal strip. U.N. officials estimate that the current number of people taking refuge exceeds 167,000.

“We don’t have the facilities, the funds to care for them long-term. Everything is scarce, and many of these people will sadly soon discover that they have nothing to return home to,” said Abu Halima of the U.N.

Gaza’s northeastern cities have been the hardest hit. It is from there that Hamas dug dozens of attack tunnels into Israel and used open areas as a launchpad for rockets. Israel Prime Minister Benjamin Netanyahu initially said the goal of Israel’s offensive into Gaza was to clear the tunnels, but military officials say the mission in Gaza has since been expanded, as Israel looks to deal a more punishing blow to Hamas.

Human rights groups, including the Israeli legal aid NGO Gisha, are already warning that the Israeli government will be loathe to allow cement back into the Gaza Strip, after hundreds of tons of cement were used to build the attack tunnels into Israel.

“Without cement, and a great deal of funds, it’s unclear how Gaza can possibly rebuild,” said Abu Halima.

Zuhair al-Ataf, a father of four, was one of them. He described gathering his family as they decided to flee the city and seek refuge at a U.N. facility. “I told them to take only what was necessary. We took medication for my daughter, jewelry. My son wanted to bring the TV, but of course that was impossible,” Ataf said. “I knew whatever we left behind would be gone, and now it is.”

Roughly 1.2 million of the 1.7 million people who live in Gaza don’t have regular access to clean water, according to a report published this week by the Emergency Water Sanitation and Hygiene, an umbrella group of 40 humanitarian groups that work in the Gaza Strip. The U.N. has also said that the aquifers that store Gaza’s water have slowly eroded over the last decade, and are on the brink of collapse. The U.N. has long been concerned about the aquifers, saying they carry a host of water-borne diseases, including polio and hepatitis. Much of Gaza’s tap water is salty — due to seawater contamination — and supplied infrequently, due to electrical outages to the pumps that are used to distribute the water.

“We tell people that only bottled water is really safe to drink, but do you know how difficult it is to provide bottled water to thousands who are displaced?” said Abu Halima. “In the current circumstances it is almost impossible.”

Mental health experts say PTSD particularly affects Gaza’s children. With over 40 percent of the population under the age of 15, hundreds of thousands of children are currently living with PTSD.

After Israel’s last offensive in 2012, the PTSD rate among children in Gaza doubled, according to the United Nation’s agency for Palestinian refugees (UNRWA).

“Doctors are still working with children who were traumatized in 2012, and those who were traumatized in the 2008 war. Now everything is being brought back again, the bombings, the airstrikes, the insecurity,” said Farid Zahalka, a doctor who works with the U.N. “It is trauma upon trauma.”