They had prepared for the worst — only to discover they didn’t know the meaning of the word.

Gut-wrenching newly released security footage from inside an Israeli hospital captures the chaos and heroism on Oct. 7, 2023 — as hundreds of traumatized and bloodied victims of Hamas’ sneak attack poured through its doors.

The footage shows wounded soldiers and civilians rushing through Soroka Medical Center as doctors and nurses scramble to treat the patients, who ranged from babies to elderly Israelis to young revelers shot at the Nova music festival — and even a heavily pregnant mom.

“At some point you realize you’re not seeing a terror attack, you’re seeing a massacre,” Prof. Shlomi Codish, CEO of Clalit-Soroka Medical Center in Beersheba, told The Post on the eve of the attack’s third anniversary.

The hospital, the only Level 1 trauma center in southern Israel, treated a staggering 674 wounded in the first 24 hours after the terror attack — more than five times the 121 casualties from the largest mass-casualty incident it had previously faced.

“The maximum number we practiced for was 300,” Codish said. “We do drills to 300, which is considered a fantastic number that we’ll never see.”

The hospital’s emergency protocols kicked in almost immediately after the attack began, with Soroka ordering 100 additional units of blood and summoning more than 1,000 staffers before 8 a.m.

“If we hadn’t done that, people would have died,” Codish said of the blood order.

By the time hospital leaders arrived, it was becoming clear that this was unlike anything they had prepared for.

“If you take the wildest horror director somewhere, they’re not going to come up with this scenario,” Codish said.

The hospital’s first operation was on a Bedouin Muslim woman in her 20s who was more than 40 weeks pregnant with her first child when she was shot in the abdomen.

Doctors saved the woman and delivered her daughter during emergency surgery, but the baby died 14 hours later.

“This is evil beyond what you can comprehend,” Codish said. “When you shoot someone with a gun, you see who you’re shooting. Someone deliberately shot a very pregnant young woman, not a soldier, who also happened to be Muslim.”

Later, soldiers brought in two babies without their parents after finding the infants alive in a room where their mother and father had been killed nearby, Codish said.

Another patient arrived in shock after watching his wife and son murdered in front of him inside a shelter at a kibbutz. He ultimately lost a leg.

“Beyond the bodily wound, how do you fathom this?” Codish said. “How does your mind wrap itself around that?”

The previously unreleased hospital surveillance footage was broadcast this week in “The Shift,” an episode of the investigative program “Zman Emet” on KAN 11, Israel’s public broadcaster.

The documentary draws on cameras throughout the hospital to show the medical center as the magnitude of the attack gradually became apparent.

In one scene, 23-year-old Golani soldier Noam is rushed down a Soroka corridor with a devastating leg injury when his father, Avraham, spots him on the stretcher.

The father runs alongside his son and manages to kiss him before doctors rush him into the trauma room. Noam survived but lost his leg.

Meanwhile, Soroka was running out of room.

The 1,200-bed hospital was already largely occupied when the wounded began arriving, forcing administrators to send hundreds of existing patients home or to other hospitals, turn internal medicine wards into surgical wards and convert open spaces into intensive-care areas.

Hundreds of frantic relatives also descended on the hospital searching for loved ones who had vanished during the attack.

“No one realized we had so many dead people in the field,” Codish said. “The heartbreaking realization over the next 24 hours was: They’re not here.”

By 6 a.m. the following morning, Soroka had identified every anonymous patient in its care, but desperate families were still holding out hope.

“As I walked down the hospital, there were ‘Have you seen?’ signs everywhere, which really reminded us of post-9/11,” Codish said.

Soroka officials knew by then that the people pictured on the posters were not among their unidentified patients, but they left the signs hanging.

“It was the only remnant of hope that people had,” Codish said.

Hospital staff photographed the posters and later learned what happened to the people pictured on them.

“Every single one of them was dead,” he said.

Eighteen people died at Soroka that day — 11 who arrived dead and seven who died during treatment.

“Every hour went by, it became apparent that this is the worst we’ve ever seen,” Codish said. “And then the next hour proved that it could be worse.”