A hot air balloon burst into flames over central Texas on Saturday after apparently striking power lines and plunged into a field, killing all 16 people aboard in one of the deadliest such accidents on record, police and eyewitnesses said.

The Federal Aviation Administration said the fiery crash occurred at about 7:40 a.m. (8.40 a.m. ET) near Lockhart, a town about 30 miles (50 km) south of Austin, the Texas capital.

The Caldwell County Sheriff’s Office said 16 people were believed to have been aboard the doomed craft and that no one survived. The Texas Department of Public Safety confirmed that 16 people were dead.

Emergency responders in Texas said the basket portion of the balloon, which carries the passenger and crew, caught fire. Aerial television footage from the aftermath of the accident showed remnants of the red, white and blue balloon, adorned with a large, yellow smiley face wearing sunglasses, lying flattened at the crash site.

The National Transportation Safety Board offered no details on what may have caused the accident, which occurred on a clear day. But a spokesman at the scene, Erik Grosof, said teams from that agency and the Federal Bureau of Investigation were being dispatched to determine how the crash unfolded.

FBI assistance is routine in cases of major accidents, Grosof said.

Margaret Wylie, an area resident, told reporters she believed that before the balloon crashed, it hit power transmission lines, which caused popping sounds like a gun going off.

“It went up like a big fireball,” she told reporters.

Grosof said the balloon was believed to have been operated by Heart of Texas Hot Air Balloon Rides, a company that serves the Austin, Houston and San Antonio areas. The sunglass-wearing smiley face and stars-and-stripes design of the fallen craft matched the pattern of a balloon featured in pictures posted on the company’s Facebook page, which carried messages of condolences.