At least 73 Palestinians were killed on Sunday while trying to get access to food, according to the Hamas-run Gaza Ministry of Health. Another 150 people were injured, Gaza health officials said.

The majority of those killed were gathered near the Zikim border between Gaza and Israel.

The Israel Defense Forces said a review is ongoing. In a statement, it said that its troops fired near crowds “in order to remove an immediate threat posed to them,” though it wasn’t specific. The IDF added that it was aware of reports of casualties but said that a “preliminary review indicates that the reported number of casualties does not align with existing information.”

Video from Al Shifa hospital in Gaza City shows numerous ambulances and donkey carts arriving at the hospital, filled with the injured and dead. The head of the hospital told Reuters in an interview, “The situation is catastrophic. We can no longer handle the influx of injuries, so we have started directing patients to other field hospitals. The situation is extremely bad and disastrous. There are so many dead and wounded, and we simply cannot treat them all.”

Gaza’s health ministry said in a statement Sunday that the region was heading toward an “unprecedented humanitarian catastrophe.” According to the United Nations, at least 875 people have been killed in Gaza while trying to get food.

On Saturday, more than 30 Palestinians were killed by Israeli gunfire near two aid distribution sites in Gaza, according to health officials. The IDF said the incident is under review.

Israel’s closure of all crossings into Gaza has now reached 140 days.

ABC News’ Victoria Beaule contributed to this report.