(CNN) -- In their first official report on the Reno air race crash earlier this month, federal accident investigators on Friday noted evidence that a small piece of the plane's tail separated shortly before the crash.

But investigators did not say whether the loss of the plane's "trim tab" was the cause or the result of the plane's violent maneuvering before it crashed into the ground, killing 11 and injuring 74.

The National Transportation Safety Board preliminary report was a straightforward recitation of facts already known in the Sept. 16 crash at Reno Stead Airport in Reno, Nev. Investigators said it typically takes about a year before the safety board rules on the probable cause of an incident.

The report notes that the modified P-51D Mustang had completed several laps and was in a steep left turn toward the home pylon when, according to photographic evidence, the airplane suddenly banked momentarily to the left before banking to the right, turning away from the race course, and pitching into a steep dive.

Witnesses reported that a piece of the airframe separated during these maneuvers, a fact confirmed by the photographic evidence, the Safety Board said.

After roll and pitch variations, the plane descended in "an extremely nose-low attitude" -- meaning at a steep angle -- and collided with the ground in the box seat area near the center of the grandstands, the board said.

The accident resulted in the death of the pilot and 10 others. Currently, 12 of the 74 people injured remain hospitalized, some in critical condition, according to hospitals who are treating victims.

It said Safety Board and Federal Aviation Administration investigators examined the wreckage on site, and the debris has been moved to a secure storage facility for further examination in the future.

As was previously announced at a news conference, the plane's ground crew noted that the plane had a telemetry system that broadcast data to a ground station and recorded it on a box on the plane. The data includes engine readings and global positioning satellite system data.

Investigators also have recovered pieces of a camera housing and multiple detached memory cards from the airplane's onboard camera that were in the debris field, the Safety Board said. The memory cards and numerous still and video image recordings were also sent to the board's Vehicle Recorder Laboratory for evaluation, but the board has not said if useful information has been recovered.

The Federal Aviation Administration and the Reno Air Race Association are parties to the investigation, the board said.