The authorities have reported that two planes have collided in midair Saturday in Boulder, Colorado, killing three people. Authorities got the first report of a plane crash around 1:30 p.m. (3:30 p.m. ET), Brough said, adding that people reported to have witnessed flames in the air in an area less than five miles from the Boulder Municipal Airport. An amateur video shows the aircraft falling to the ground.

In addition, it is reported that one of the planes, a single-seat Piper Pawnee, was towing a glider.

Rick Brough of the Boulder County Sheriff's Office has reported that the pilot of the Piper had died in the collision. The second aircraft involved in the collision was a Cirrus SR 20. Two people on that plane also died, he added.

However, the glider managed to cut loose its cable and land safely.

"I was in my house and I heard a loud bang," iReporter Zac Mitchell, of Boulder, told CNN. "I looked out my window and saw a giant fireball in the sky."

Brough posted that a parachute did deploy from one of the planes, but that no one was attached to it.

The National Transportation Safety Board and the Federal Aviation Administration have initiated the investigating into the incident.