Armored vehicles surround an SUV used by the husband and wife terrorists in the San Bernardino, Calif., attack on Dec. 2, 2015. (AP)

A report released Friday contains chilling new details of the December assault by a husband and wife in San Bernardino, Calif. — the third deadliest attack on U.S. soil since Sept. 11, 2001 — that left 14 people dead and 22 others seriously injured.

Much of the material in the new study by the Police Foundation and the Justice Department’s Office of Community Oriented Policing Services has been previously reported by news organizations. But the 135-page report does offer new insight into law enforcement’s response and the frenzied gun battle four hours later, when Syed Rizwan Farook, and his wife, Tashfeen Malik, were killed by police.

The review found that some of the victims and witnesses had had active shooter training in the very room where they were shot and at first thought it was another training exercise when the terrorists burst in at 10:59 a.m. Dec. 2.

The report describes in graphic detail what first responders found when they entered the Inland Regional Center room, already decorated for the Christmas holiday.

“The four officers stared into the conference room,” the report says. “It looked like a bomb had gone off. Bodies were strewn across the floor. Many had devastating wounds. Blood was everywhere. The smell of gunpowder filled their nostrils, and the sprinklers sounded like they were hissing.”

In the chaos, a round hit a fire sprinkler pipe, and watered poured from the ceiling.

The officers, hewing to their training, kept searching for the killers even as the wounded grabbed their legs: “It was the worst thing imaginable — some people were quiet, hiding, others were screaming or dying, grabbing at your legs because they wanted us to get them out, but our job at the moment was to keep going.”

The deluge from the sprinklers in the conference room made it impossible for a medic to use traditional triage tags on the injured, so the medic used tape and wrote each person’s status on the tape. Initially, the wounded were carried to a spot right outside the building, but that was judged too close to an active and dangerous crime scene. They were then carried — many soaking wet and slippery — across the street to a golf course. Ultimately, 22 people, many of them critically injured, were taken to a hospital within 57 minutes of the shooting, and all survived.

Farook, 28, a U.S. citizen born to Pakistani parents, and Malik, 29, were dressed all in black during the attack. Law enforcement officials have previously said that the pair pledged allegiance to the leader of the Islamic State. The pair fired more than 100 .223 rounds “in a matter of minutes,” according to the report, before fleeing the scene in a rented SUV.

The review, which was first reported on by the New York Times, describes the law enforcement response as professional but sometimes chaotic because of the many different agencies involved, uncertainty about the location of the shooters and confusion about which rooms had been cleared at the center.

Communications centers were inundated with calls, and police radio traffic was so overwhelmed that some officers could not find a clear channel on which to communicate. The San Bernardino County Sheriff’s Department set up a 1-800 number for people to call for information about their loved ones, but the number was broadcast before any staff workers were there to answer calls.

Hours later, 175 officers arrived at the scene of the final gun battle with Farook and Malik on San Bernardino Avenue, where a patrol sergeant had spotted the pair. Twenty four officers fired at least 440 rounds. The suspects fired at least 81.

Malik died after she was struck by 15 bullets, two in her head. Farook, who stepped out of the SUV, had 25 wounds, most to his legs but also one that fragmented into his neck.

According to the report, the terrorists did not wear body armor. Their all-black tactical-looking clothing included “airsoft neck guards” that the report says are used to stop plastic pellets in warfighting simulation games but can’t stop a real bullet.

Matt Zapotosky contributed to this report.