A United Airlines flight diverted to Salt Lake City last week after the pilots discovered a crack in one of the layers of the windshield, and a weather balloon may have been what caused the crack, according to the company that owns the balloon.

The National Transportation Safety Board, which is investigating the incident, told CBS News Sunday that the windscreen of United Flight 1093, which was en route Thursday from Denver to Los Angeles, was being sent to its laboratory for examination. 

The multilayer windshield is designed to continue to function in case one of the layers is damaged, according to officials.

NTSB Investigators are trying to determine if something struck the windshield of the Boeing 737 mid-flight and if so, what that object was. As part of the investigation, the NTSB was to speak to the pilots about what they saw and review any available flight voice and data recorder details.

In a social media post late Monday, John Dean, CEO and co-founder of Palo Alto, California-based WindBorne Systems, said he believes it was one of the company’s weather balloons that struck the aircraft’s windshield.

“I think this was a WindBorne balloon,” he said. “We learned about UA1093 and the potential that it was related to one of our balloons at 11pm PT on Sunday and immediately looked into it. At 6am PT, we sent our preliminary investigation to both NTSB and FAA (Federal Aviation Administration), and are working with both of them to investigate further.”

Dean said WindBorne “operates a constellation of long duration lightweight weather balloons to improve weather forecast, with much of our data going to both US and international governments. … We haven’t yet received any operational guidance. Regardless, we just deployed a software change to minimize time at active flight levels and are manually checking it” with all the company’s airborne ballons.

There were 134 passengers on the flight and six crew members, according to United. The airline said the plane landed safely in Salt Lake City, and another aircraft transferred the passengers to Los Angeles. 

Much of the NTSB and FAA communications staff are furloughed due to the ongoing government shutdown.