As Israeli ground forces continue to carry out an hourslong raid on the largest hospital in the Gaza Strip on Wednesday, staff there told ABC News that none of the patients have been moved out.

There are about 600 patients admitted to Al-Shifa Hospital in Gaza City, many of whom are seriously ill or wounded. Thousands of other people have been sheltering in the vast medical complex amid Israel's bombardment of the area.

Speaking to ABC News via telephone from inside the hospital, Dr. Ahmed Mokhallalati described the moment Israeli troops arrived at the complex before dawn on Wednesday.

"They told us no one should look through the windows," said Mokhallalati, who is the head of the hospital's plastic surgery department.

"The whole situation is really horrible," he added. "They are just scaring everyone here."

-ABC News' Dragana Jovanovic

A senior Israeli defense official said Wednesday that so far Israeli troops have not engaged in combat inside Al-Shifa Hospital itself and suggested they have not yet encountered Hamas fighters within the vast medical complex, the largest in the Gaza Strip.

However, the Israel Defense Forces' ground operation at Al-Shifa Hospital in Gaza City is ongoing and they have allegedly found evidence -- specifically weapons -- that Hamas, the militant group that rules the strip, is operating inside there, according to the official. More details will be revealed later Wednesday, the official said.

Hamas has since released a statement calling Israel's claim that it found weapons inside Al-Shifa Hospital "a blatant lie."

The senior Israeli defense official told reporters that Israeli soldiers went into Al-Shifa Hospital to destroy Hamas infrastructure, not to go after Hamas leaders.

The official noted that four Hamas fighters were killed near the medical complex as Israeli troops approached, but said they are still investigating if they came from inside the hospital.

The official said Israeli forces are currently operating only in "one area" of the hospital but warned that they will enter other areas as needed. The IDF has "no intention" of sending its soldiers to fight "among the patients or the active personnel of the hospital," according to the official.

The official told reporters that the hospital's youngest patients -- dozens of premature babies -- are in a building of the complex not where Israeli troops are currently operating. Israeli soldiers delivered incubators and baby food at the front gate of the hospital in hopes that the staff there would take them, according to the official.

The official declined to say where exactly Israeli forces were operating within the complex, citing operational security.

Al-Shifa Hospital was designed by Israeli architects decades ago and the IDF knows its layout well.

-ABC News' Jordana Miller, Patrick Reevell and Joe Simonetti

The head of the United Nations' humanitarian relief operations condemned on Wednesday the Israeli military’s ongoing raid on the Gaza Strip's largest hospital, saying he is “appalled” by the reports of the operations.

"I'm appalled by reports of military raids in Al Shifa hospital in #Gaza. The protection of newborns, patients, medical staff and all civilians must override all other concerns. Hospitals are not battlegrounds," U.N. Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator Martin Griffiths wrote in a post on X, the social media platform formerly known as Twitter.

-ABC News' Patrick Reevell

The Israel Defense Forces said Wednesday morning that its ground troops are continuing to carry out "a precise and targeted operation against Hamas in a specified area" of the largest hospital in the Gaza Strip.

"The activity in this specified area is based on operational necessities, as well as intelligence information that indicates Hamas terrorist activity is being directed from the area," the IDF said in a statement. "Prior to their entry, the IDF troops encountered explosive devices and terrorist cells, and an engagement began in which terrorists were killed."

The raid on Al-Shifa Hospital in Gaza City began early Wednesday around 3 a.m. local time, after Israeli forces had moved closer to the medical complex for several days. Gaza's Hamas-controlled Ministry of Health said gunfire was heard on the hospital grounds and Israeli troops entered through the main building and the emergency department.

Thousands of civilians, along with hundreds of patients -- most of whom are seriously ill -- have been sheltering at Al-Shifa, according to hospital staff and Gaza health officials.

The IDF alleges that Hamas has placed its command centers under Al-Shifa and other hospitals in Gaza and is deliberately sheltering behind Palestinian civilians -- claims which the militant group denies.

The IDF said Wednesday that its troops "are conducting searches for Hamas terror infrastructure and weapons" at Al-Shifa Hospital. They also "delivered humanitarian aid to the entrance of the hospital," according to the IDF.

Doctors at Al-Shifa Hospital have been warning of its imminent collapse due to a lack of electricity as well as limited fuel and medical supplies.

-ABC News' Joe Simonetti, Sohel Uddin and Morgan Winsor

Patients and doctors evacuated the Al-Shifa hospital on Saturday, after the Hamas-run Gaza Health Ministry claimed Israel forced them to leave. The IDF released a statement denying it ordered the evacuation, but in a Friday briefing another spokesperson said the IDF was urging anyone left in Al-Shifa hospital to leave and that it hoped it would take place in the "next few hours."

Doctors described their exodus from the hospital to ABC News, with Dr. Ahmed Mokhallalati -- who is still in the hospital -- saying "all critical ICU patients have died. The situation is terrifying."

"Today early in morning people were forcefully evacuated from the hospital, with absolutely no plan of evacuation of the patients and the medical staff. Most of the civilians together with most of the staff left the hospital," Mokhallalati said.

Mokhallalati said there are around 300 patients, who cannot move, and less than 50 medical staff still in the hospital.

"There are still 33 premature babies in the hospital -- one baby died yesterday, and two babies were taken by their parents to evacuate with them. There is only one neonatologist and one nurse with them," he added. The Israelis have provided only three transport incubators for 33 babies. So, if they tell us 'you have to evacuate now,' I have no idea how to evacuate them."

Dr. Adnan Al-Barash, head of the orthopedic department at Al-Shifa Hospital, told ABC News that the "Israeli army forced us to leave the hospital at gunpoint."

"The path for us to walk was set out among the tanks, we had elderly, wounded… The scene was very tragic and sad," Al-Barash said.

"We went out between the tanks, and we could not get the wounded out on the broken roads and we could not move wheelchairs for the wounded," he added.

-ABC News' Dragana Jovanovic and Zoe Magee