GAZA  A dentist stood at the bed of a doctor, his good friend Ehab Madhoun, 32, who had just died, his shrapnel-pitted body wrapped in a white shroud.

The day before, Dr. Madhoun, a general practitioner, was in an ambulance responding to an Israeli strike at the Jabaliya refugee camp in northern Gaza. Another missile hit the ambulance. The driver, Muhammad Abu Hasira, died instantly. Dr. Madhoun lingered for a day, dying of his wounds on Wednesday in the intensive care unit of Shifa Hospital, where hundreds of people have been brought since Israel began its heaviest assault on Gaza in three decades.

The dentist cried.

“He was just doing his work,” said the dentist, who would not give his name. “He’s a doctor, and I can’t understand why Israel would hit an ambulance. They can tell from the cameras it’s an ambulance.”

It has always been this way, over years of conflict here, that civilians are killed in the densely populated Gaza Strip when Israel stages military operations it says are essential for its security. But five days of Israeli airstrikes have surpassed past operations in scale and intensity; the long-distance bombardment of the Hamas-controlled territory has, however well aimed at those suspected of being militants, splintered families and shattered homes in one of the most densely populated places on Earth.