Cutting through that farmland is a row of massive high-capacity electrical transmission lines about 4 to 5 stories tall. The site of the crash appears to be right below the overhead lines, though authorities haven’t provided further details about what happened. Aerial photos showed an area of charred pasture underneath power lines.

Margaret Wylie lives about a quarter-mile from the crash site and told The Associated Press that she was letting her dog out Saturday morning when she heard a “pop, pop, pop.”

“I looked around and it was like a fireball going up,” she said, noting that the fireball was under large power lines and almost high enough to reach the bottom of them.

Wylie, who called 911, said the weather seemed clear and that she frequently sees hot air balloons in the area.

Erik Grosof with the National Transportation Safety Board said at a news conference that the agency has deemed it a major accident and a full-bore investigation will begin today when more federal officials arrive. “This will be a difficult site for us to work through,” Grosof said.

The balloon was operated by Heart of Texas Hot Air Balloon Rides, according to two officials familiar with the investigation.

Heart of Texas’ website said it offers rides in the San Antonio, Houston and Austin areas. The company’s Facebook page features photos of a hot-air balloon with a smiley face with sunglasses on it up in the air, people waving from a large basket on the ground and group selfies taken while up in the air.

The operation does not appear to be registered with the state of Texas.

Authorities have not released the names of those who were on board and have not said who was flying the balloon.

Skip Nichols identifies himself on his Facebook page as the chief pilot of Heart of Texas and pictures posted by him are on the business’ Facebook page. Nichols, 49, is also the registered owner of Missouri-based Air Balloon Sports LLC. No one answered the door at a home in Kyle, Texas, believed to be his.

Warning about potential high-fatality accidents, safety investigators recommended two years ago that the Federal Aviation Administration impose greater oversight on commercial hot air balloon operators, government documents show. The FAA rejected those recommendations.

Speaking to the AP just before leaving for Texas to lead the crash investigation, NTSB board member Robert Sumwalt said his team was still trying to gather basic information about the accident.

FAA spokesman Lynn Lunsford said it’s difficult to say whether the Texas crash will cause the agency to reconsider NTSB’s recommendations “until we’ve had a chance to gather and examine the evidence in this particular case.”