A blimp hovering over the US Open at Erin Hills in Wisconsin reportedly caught fire before crashing to the ground with the pilot forced to flee from the burning airship.

Spectators of the prestigious golfing tournament gasped as the huge blimp plummeted to the ground with the pilot injured in the fall, suffering serious burns.

It was originally reported that the sole pilot had parachuted out of the blimp but the president of AirSign, the aerial advertising firm that owned the blimp, said that the pilot rode the blimp to the ground.

The NBC affiliate in Milwaukee, WTMJ-TV, reported that the pilot was on the ground and in retreat when the propane exploded.

While the Milwaukee Journal-Sentinel reported that the blimp appeared to catch fire just before hitting the ground near a highway outside the course.

The pilot was pictured on a stretcher leaving the area and was taken to hospital by helicopter, they added.

One onlooker, Bryan Rosine, told the newspaper: "It started deflating, and then it started going down.

"They were trying to give it some throttle and it didn't go up. Then there was a bunch of kabooms and smoke clouds."

AirSign said in a Tweet after the incident: "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."

The 117th US Open began on 12 June with Rory McIlroy, Justin Rose and Rickie Fowler all gracing the greens until Sunday.

The USGA said in a statement: "According to local authorities, a commercial blimp not affiliated with the USGA or the U.S. Open Championship broadcast crashed in an open field approximately a half mile from the Erin Hills golf course at approximately 11:15 a.m. 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."