Israeli forces raided the last operational hospital in northern Gaza overnight Sunday, according to Gaza’s health ministry and hospital officials, who added that several medical staff members had been briefly detained.

Israel released 21 medical staff members at Al-Awda Hospital after holding them for three hours, according to a statement by Al-Awda Health and Community Association, which runs the hospital. The group said that the hospital’s director, Dr. Ahmed Muhanna, remained in Israeli custody.

The health ministry said that the detainees had been stripped and interrogated, calling the conditions “inhumane.”

The Israeli military did not immediately comment on the accounts of the association and the health ministry. Israel has in the past defended the mass detention of men in northern Gaza, saying it needed to strip them to check for explosives and to interrogate them to determine if any were connected to Hamas.

The ministry added that it was worried Israeli forces would repeat the scenes that took place at Kamal Adwan Hospital, where Israeli forces destroyed part of its building and interrogated staff members for a week, according to the health ministry and two people at the scene.

The Israeli military defended its actions at Kamal Adwan, saying the hospital was being used by Hamas as a command and control center and asserting that it had detained about 80 fighters. Gazan health officials said that some of the hospital’s workers, including its director, were among the detained.

Hamas and medical staff at other Gaza hospitals have denied Israeli allegations that hospitals have been used by the armed Palestinian group. The Israelis say they have uncovered tunnels and weapons, including at the territory’s largest hospital complex, Al-Shifa, that it considers proof of its allegations.

The health ministry said on Monday that no more hospitals were operational in the northern strip after both Kamal Adwan and Al-Awda went out of service following Israeli raids. Both hospitals had severely limited their operations over the last few weeks because of nearby ground fighting and a severe lack of fuel and supplies.

According to health officials in Gaza, more than 90 medical workers have been detained since Israel began its bombardment and ground invasion of Gaza, including the director of Al-Shifa Hospital, Dr. Mohammed Abu Salmiya. The health ministry said on Monday that Dr. Salmiya remained in detention and was being interrogated in “starvation and extreme cold.”

A volunteer at Kamal Adwan Hospital, Osama Al-Absi, said in an interview on Sunday that he was among those detained and later released by Israeli forces. He said the detainees were taken to an Israeli military base in Gaza, stripped, and left in a ditch for hours. “Most of us were beaten and insulted,” he said.

Al-Awda Hospital, in the northern neighborhood of Jabaliya, had been surrounded by Israeli soldiers and tanks for nearly two weeks as ground fighting raged nearby, according to the association that runs it.

It added that 43 patients and 96 staff members had been “trapped inside the hospital” for at least some of last week, and said that the hospital had been hit by Israeli gunfire and artillery over the last two months.

The few hospitals that remain operational in the south have also been hit in recent days.

The Nasser Medical Complex in southern Gaza’s largest city, Khan Younis, was hit by an unexploded Israeli artillery shell on Sunday, with shrapnel and debris killing a 13-year-old and wounding three others, according to the health ministry. The child, Dunia Abu Muhsen, had lost her leg in a strike on her home that killed her father, mother and two of her brothers a few weeks ago and was receiving treatment at the hospital when she was killed, the ministry said.

The Israeli military did not immediately comment on the description of what happened.

Ameera Harouda contributed reporting from Doha, Qatar.