Prof. Alon Pikarsky waited outside of Hadassah Hospital Ein Kerem on Monday, as the wail of the ambulance came closer. It was his job to triage the patients.

In his 35 years working for Hadassah, Prof. Pikarsky, head of general surgery, had seen his share of trauma, but nothing like this. In the two days since Hamas terrorists began their brutal attack on Israel, the hospital had already treated more than 60 patients, civilian and military, at least half with severe injuries.

That morning, a mosque in the town of Abu Ghosh, just outside of Jerusalem in the Jerusalem Hills, had been attacked by a missile from Gaza.

Opening the ambulance doors, it was immediately clear that this patient, a 20-year-old Muslim man who had been praying in the mosque when the missile hit, needed critical care immediately.

“He came with no pulse, no life, he was clinically dead,” Prof. Pikarsky recounted during a live briefing held by Hadassah on Thursday. “I shouted to [my colleague], listen, replace me in the triage, I’m taking this patient to the operating room immediately.”

The operation lasted more than two hours.

“He had severe injuries, very severe injuries, to the main blood vessels, both the veins and the arteries in the abdomen and other organs as well,” Prof. Pikarsky said.

He managed to stabilize the patient, but had to operate on him again on Tuesday and still again on Wednesday. On Thursday, he remained in critical condition in the ICU and was among 20 patients treated at the hospital after the mosque attack.

“We pray for his life,” Prof. Pikarsky said, wearing purple scrubs, his surgical mask at the ready as he prepared to leave the briefing and head right back into surgery for the next patient.