UN rights chief Volker Turk has said he was “horrified” by the destruction of the Nasser and Al Shifa medical facilities in Gaza and reports of mass graves containing hundreds of bodies there, according to a spokesperson.

According to Reuters, Palestinian authorities reported finding bodies in mass graves at a hospital in Khan Younis this week after it was abandoned by Israeli troops. Bodies were also reported at the Al Shifa site following an Israeli special forces operation.

“We feel the need to raise the alarm because clearly there have been multiple bodies discovered,” said Ravina Shamdasani, the spokesperson for the United Nations High Commissioner for Human Rights.

“Some of them had their hands tied, which of course indicates serious violations of international human rights law and international humanitarian law, and these need to be subjected to further investigations.”

She added that the UN human rights office was working on corroborating Palestinian officials’ reports that 283 bodies were found at Nasser and 30 at Al Shifa. According to those reports, the bodies were buried beneath piles of waste and included women and older people.