LOCKHART, Texas >> A hot air balloon made contact with high-tension power lines before crashing into a pasture in Central Texas, killing all 16 on board, according to federal authorities who are investigating the worst such disaster in U.S. history.

A power line was tripped at 7:42 a.m. Saturday, and the first call to 911 came a minute later, National Transportation Safety Board member Robert Sumwalt said during a news conference. The crash site was near a row of high-tension power lines, and aerial photos showed an area of scorched land underneath. One witness described to The Associated Press seeing a “fireball” near the power lines.

The NTSB will look at all factors that might have played a role, including weather, but is concentrating on gathering “perishable evidence, the evidence that goes away with the passage of time,” Sumwalt said, noting some of that is witness statements that can fade with time.

“This wreckage will not be here more than another day or so,” he added.

The pilot was Skip Nichols, 49, said Alan Lirette, who identified Nichols as his best friend, roommate and boss. Lirette said he helped launch the balloon, which was carrying a total of 16 people, none of them children. The NTSB has not yet publicly identified the pilot or the passengers.

Matt Rowan and his wife, Sunday Rowan, were among those on board the hot air balloon. His brother, Josh Rowan, said that as the two prepared to take the balloon ride they texted family and posted on social media pictures of the balloon set up, the rising sun, them in the basket.

“It’s a bit haunting now but I guess it was a bit of a play-by-play,” Josh Rowan told The Associated Press on Sunday.

He said the two, both 34, lived in San Antonio and just got married in February. “They were really happy and they were in love and they were really starting a life together,” he said.

The NTSB said the balloon was run by Heart of Texas Hot Air Balloon Rides. Nichols’ Facebook page identifies himself as the chief pilot of that business, which does not appear to be registered with the state of Texas.

The passengers met the balloon operator in the San Marcos Wal-Mart parking lot at about 5:45 a.m. Saturday, and traveled to Fentress Texas Airpark. Ground crew members told the NTSB that they launched about 20 minutes after the expected 6:45 a.m. time, communicated with the balloon by cellphone and the pilot navigated with an iPad.

The balloon traveled about 8 miles from takeoff to crash, and the basket was found about three-quarters of a mile from the balloon material itself.

Caldwell County Sheriff Daniel Law said in a statement that NTSB and medical professionals have said identification of the victims will be “a long process.”

An online Federal Aviation Administration database said an Alfred G. Nichols of Chesterfield, Missouri, was medically certified to fly in 1996 and was rated a commercial pilot of lighter-than-air balloons on July 14, 2010. The rating is limited to hot air balloons with an airborne heater. Missouri records also listed Nichols as the owner of Air Balloon Sports LLC, based from the same Chesterfield address as the FAA record.

Lirette said Nichols went by the first name of Skip. Speaking to the AP from a house he shared with Nichols in Kyle, Lirette would not answer specific questions about the balloon’s launch or its crash.

“That’s the only thing I want to talk about, is that he’s a great pilot,” Lirette said of Nichols. “There’s going to be all kinds of reports out in the press and I want a positive image there too.”

Wendy Bartch, a former girlfriend of Nichols, told the Austin American-Statesman that he was “a good pilot and loved people,” was cautious about keeping passengers safe, and had been involved with hot air balloons for about two decades.

Philip Bryant of Ballooning Adventures of Texas in Richmond, which also does inspections and maintenance for other operators, said the balloon had “very good equipment, very new equipment.” Nichols brought his balloon into his inspection facility in May 2014 and was issued a one-year recertification, Bryant said. The manufacturer of Nichols’ balloon mandates an annual inspection, he said, adding that he couldn’t do it this year but believes Nichols took it to another inspector.

Bryant said Nichols told him he moved from the St. Louis area to Texas because there was less competition.

Numerous calls to Heart of Texas operations manager Sarah Nichols, 72, rang unanswered, and a woman in Missouri believed to be the pilot’s sister did not return phone calls.

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

NTSB investigators will look at “three things — human, machine and environment,” Sumwalt reiterated Sunday afternoon. The investigation will include the balloon’s maintenance history and the weather at the time of the crash.

They also will look into whether the operator filed a passenger manifest before taking off, Sumwalt said.

Crews recovered 14 personal electronic devices, including cellphones, and iPad and three cameras, which will be sent to the NTSB’s lab in Washington for investigation.

Margaret Wylie, who lives about a quarter-mile from the site, told AP she was letting her dog out when she heard a “pop, pop, pop” and saw what looked “like a fireball going up.”

Safety investigators recommended two years ago that the FAA impose greater oversight on commercial hot air balloon operators, government documents show. The FAA rejected those recommendations, and the NTSB classified the FAA’s response as “open-unacceptable,” which means the safety board was not satisfied with it.

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.”

Saturday’s crash was one of the worst hot air balloon accidents on record. In 2013, 19 people were killed and two were injured when a balloon caught fire over Luxor, Egypt, and plunged 1,000 feet.