The top U.S. commander in Afghanistan acknowledged Wednesday that “human error” was to blame for a U.S. warplane’s fatal strike on a charity hospital in Afghanistan last month, as the official military investigation determined the crew confused the hospital for another building several hundred yards away.

“This was a tragic but avoidable accident caused primarily by human error,” Gen. John Campbell told reporters on Wednesday.

Campbell said the report detailed a series of errors as well as technical and procedural problems, all of which contributed to the strike, which killed and wounded dozens of civilians.

He also said the individuals “most closely associated with the incident have been suspended from their duties” pending further consideration.

The report itself, obtained by The Associated Press, said the crew of the U.S. AC-130 gunship relied on a physical description of the compound provided by Afghan forces, which led the crew to attack the wrong target. It said the intended target, thought to be under Taliban control and being used in part as a prison, was 450 yards away from the hospital.

Investigators found no evidence that the crew or the U.S. Special Forces commander on the ground who authorized the Oct. 3 strike knew the targeted compound was a hospital at the time of the attack.

The attack was preceded, according to the report, by Afghan special forces members advising the U.S. Special Forces commander in Kunduz that an Afghan ground assault force would raid a National Directorate of Security compound in Kunduz that night. The NDS is Afghanistan's national intelligence agency.

The Afghans identified the compound as a Taliban insurgent command and control site, the report said. The AC-130 aircrew, however, for a variety of reasons thought the Afghans were referring to the site that turned out to be the hospital. The coordinates for the target were passed on to the aircrew by an American terminal attack controller, including a reference to the target as also being a prison.

But Campbell cited “multiple errors” that led to hitting the hospital instead.

He noted that the gunship left earlier than planned for its mission, and did so without getting a normal mission brief and securing vital materials like information that would have identified the location of the Doctors Without Borders hospital.

Further, there was an equipment malfunction that eliminated the ability of the aircraft to transmit video or electronic messages. In addition, Campbell said, the AC-130’s targeting systems were degraded in their accuracy because the aircraft had moved from its original path due to a suspected missile threat.  And when the crew entered the coordinates for the originally intended target, the coordinates correlated to an “open field.”

The crew then chose the closest, largest building near that field – which was the trauma center, and not the intended target. Once over Kunduz, the crew focused on the physical description of the facility, and not the grid coordinates. 

“Tragically, misidentification continued throughout the remainder of the operation,” Campbell said.

He said the attack started at 2:08 a.m. that morning, and an officer got a call at 2:20 a.m. advising the medical facility was under attack – it took until 2:37 a.m. for the crew to “realize the fatal mistake.” The attack lasted about 29 minutes, Campbell said, and killed 30 people and injured dozens.

Investigators also found the crew did not observe hostile activity at the trauma center itself.

Military officials stressed that they would never intentionally target a hospital.

The investigation, known officially as a combined civilian casualty assessment, was led by U.S. Army Brig. Gen. Richard Kim and was composed of representatives of NATO and the Afghan government. It was charged with determining facts surrounding the incident but not to assign blame. A subsequent U.S. military investigation was done to look further at the case and to determine accountability.

Following the release of the report, Doctors Without Borders reiterated its call for an “independent and impartial investigation” into the attack.

"The U.S. version of events presented today leaves MSF with more questions than answers,” Christopher Stokes, the organization’s general director, said in a statement. “… It appears that 30 people were killed and hundreds of thousands of people are denied life-saving care in Kunduz simply because the MSF hospital was the closest large building to an open field and 'roughly matched' a description of an intended target. The frightening catalogue of errors outlined today illustrates gross negligence on the part of U.S. forces and violations of the rules of war.”

Doctors Without Borders, known by its French initials MSF, said earlier this month in its own report that several doctors and nurses were killed immediately, and patients who could not move burned to death in the ensuing fire. Hospital staff members made 18 attempts to call or text U.S. and Afghan authorities, the group said.

People fleeing the main building were cut down by gunfire that appeared to track their movements, while a patient trying to escape in a wheelchair was killed by shrapnel, the MSF report said.

According to officials, the incident happened after U.S. special operations forces were already fighting the Taliban in Kunduz at a police compound for nearly five consecutive days and nights. 

A copy of the casualty assessment report was obtained by The Associated Press on Wednesday. It has not been publicly released.

The report said investigators found no evidence that the Americans involved knew they were attacking a hospital. It is unclear whether the U.S. Special Forces commander on the ground, who authorized the air assault, had the map grid coordinates for the hospital available to him at the time he authorized the attack, the report said. The medical charity had provided GPS coordinates for its medical facilities in Kunduz to U.S. military authorities in Kabul and to Afghan government officials on Sept. 29.

"The misidentification of the MSF compound and its subsequent engagement resulted from a series of human errors, compounded by failures of process and procedure, and malfunctions of technical equipment which restricted the situational awareness" of the U.S. forces involved, the report concluded.

President Obama has apologized for the attack, one of the worst incidents of civilian casualties in the 14-year history of the U.S war effort.

The Associated Press contributed to this report.