A statement from the Washington County Sheriff's Office said its initial investigation shows the blimp may have experienced mechanical problems before the crash.
A deputy at a security post reported seeing the aircraft on fire or smoking and rapidly descending about 11:15 a.m., the Sheriff's Office said. First responders used utility vehicles to reach the crash site, which was an open field about a half mile from the Erin Hills golf course.
Aerial video from a television news helicopter shows pieces of the flattened blimp on the field along with charred metal and grass.
The first responders transported the injured pilot to a waiting medical helicopter that had landed in the field. Sheriff's officials said the pilot was the only one on board.
Golfer Brandt Snededker said he spotted something while on the course.
"Yeah. My caddie made a comment on the 9th hole. He said the blimp is not looking good. I guess it was nose down. I saw a puff of black smoke. I didn't know it was the blimp. It's not good. Glad everybody is OK," Snededker said after finishing his round.
The blimp, operated by Florida-based AirSign, was used for advertising as it floated above the golf tournament and had been airborne for several hours before it went down, authorities said.
Justin Maynard, a sales manager for AirSign, said the company's operations team on the ground in Erin had no more definitive information on pilot's condition, other than the pilot was expected to be OK. Maynard could not confirm witness accounts that the pilot skydived from the blimp and said the aircraft's pilots do not regularly carry parachutes.
The Federal Aviation and Administration and National Transportation Safety Board have been called to investigate the crash. The Sheriff's Office said the FAA determined the aircraft was operating at the proper altitude.
The Open is one of golf's four majors.
The Associated Press contributed to this report.