A small plane clipped the towline of another plane pulling a glider Saturday, sparking a fiery midair crash in Colorado and killing at least three people, authorities said.
Boulder County officials suspended a search for victims overnight.
"The investigation is still preliminary, but we do know we have three confirmed dead," said Rick Brough, spokesman for Boulder County sheriff's department. "We're saying there is a possibility of five total because one plane seated five. We just don't know how many people were flying."
Brough said the tow airplane, a Piper Pawnee, and the other aircraft, a Cirrus SR20, "caught fire midair and fell to the ground."
The glider disconnected from the plane just before the second plane hit the tow rope, Brough said.
"We understand the glider went through a fireball after the impact," NTSB field investigator Jennifer Rodi said.
The glider landed safely — with no injuries to anyone on board — at a nearby airport just after the planes made impact, authorities said.
The Piper belonged to Mile High Gliding Inc. and had just taken off from Boulder Municipal Airport when the accident happened. A woman who answered the phone at the glider company declined to comment.
Gliders, or sailplanes, are lightweight aircraft that are often towed into the sky, then released to glide to the ground.
The crash spread debris over a 1½ mile region, scorching several sections of prairie in the Rocky Mountain foothills. The crash happened near a suburban area dotted with homes and businesses, but no one on the ground was injured.
The Cirrus SR2 was equipped with an emergency parachute system, which allows small planes to descend slowly to the ground in case of an emergency.
A witness's video on MSNBC showed the plane in its descent to the ground trailing thick, black smoke and a parachute.
One witness, Christian Sterner, said he saw two big balls of flames, including one attached to a parachute.
Other witnesses reported smoldering wreckage in at least three areas on the prairie north of Boulder, which sits at the foothills of the Rocky Mountains. Aquina Rogers, a worker at a storage facility in the area, said she could see a wing in one of the wreckage fields.
The three dead came from both of the planes that crashed, Brough said. Authorities were trying to confirm how many people were flying in each plane.