It wasn’t known what might have caused the crash between the four-seater Cessna 172 and the Sonex Xenos, a light, aluminum, homebuilt aircraft that can seat two.
Nearby residents who heard the crash and rushed outside told CBS affiliate 9News in Denver they were surprised the planes could have struck each other on such a clear morning.
Neighbors said they saw the two planes collide while they were eating breakfast just before 9 a.m.
“Yeah, it looked like it was in trouble because usually planes like that don’t go straight down. It hit and there was no fireball – there was nothing, it just crumpled in and it was gone,” Sean Tufts said.
The collision happened after the Cessna plane made a 360-degree left turn, and then made a right turn, east — hitting the other plane.
One of the planes crashed in a field, the other in a stand of trees, near Vance Brand Airport in Longmont, Colorado, about 30 miles north of Denver. Two people were found dead in one wreckage, and one person in the other, the Boulder County Sheriff’s Office said.
The Federal Aviation Administration and the National Transportation Safety Board are investigating. The NTSB said a preliminary report would be released in about 15 days.
Neither aircraft was in contact with air traffic control, and each plane was equipped with collision avoidance systems to alert each pilot of other aircraft in the area.
According to NTSB, the two pilots in the Cessna aircraft — one a student pilot — were coming from the Rocky Mountain Metropolitan Airport, northwest of Denver. The other plane was coming from the town of Hudson, which is just east of Denver.
The identities of the victims were not immediately released.
The Associated Press contributed to this report.