WATCH - Blimp crashes at the US Open in Erin Hills after catching fire
An investigation has been launched after a blimp deflated, burst into flames and crashed on Thursday morning near the US Open at Erin Hills.
Spectators posted photos and videos online which appeared to show the blimp falling from the sky and crashing in woodland near the course.
American Jamie Lovemark, who saw the crash while compiling an opening 69, said: "I was teeing off on maybe number five and I looked up and saw it on fire and I felt sick to my stomach. I had the shakes.
"I felt terrible for the people inside. I didn't know what was going on. It was a horrible sight. I don't know what happened. I hope the guys got out okay.
"It was a horrific scene. I've never seen a plane crash, blimp crash, anything like that. So it was pretty awful. I thought they might stop play. It was scary."
Fox Sports broadcast footage of an explosion from the downed blimp, which was operated by AirSign, an aerial advertising firm with operations across the United States.
A spokesman for AirSign told the Milwaukee Journal Sentinel: "The pilot is okay but suffered some burns. He stayed with the blimp until it went down."
The company later tweeted: "Thanks to everyone for your concerns, the blimp pilot is being taken to the hospital but is expected to be ok. No details on cause of crash."
Terry Williams, a spokesman for the National Transportation Safety Board, said the agency has launched an investigation into the incident and has sent an investigator to the scene.
A statement from tournament organisers, the United States Golf Association (USGA), read: "According to local authorities, a commercial blimp not affiliated with the USGA or the US Open Championship broadcast crashed in an open field approximately a half mile from the Erin Hills golf course at approximately 11:15am CDT.
"First responders were quick to arrive at the scene and the pilot is currently being treated for unknown injuries.
"No other people were involved in the incident and local law enforcement is currently investigating. Our thoughts and prayers are with the pilot at this time."