The crash happened at Wimberley, a city about 65km southwest of Austin, the Texas Department of Public Safety said.
"The pilot and four passengers on board were pronounced deceased on scene," Sergeant Billy Ray told reporters.
The names of the victims have been not released, Hays County Judge Ruben Becerra said in a post on Facebook.
The Amarillo Pickleball Club confirmed the victims were members who were flying to a tournament.
The Cessna 421C took off from Amarillo and was headed to New Braunfels National Airport, according to the flight history.
Aerial photos posted online by the Austin American-Statesman showed the aircraft completely destroyed in a wooded area.
Ray said the Federal Aviation Administration and the National Transportation Safety Board were leading the investigation.
At least one pilot in the area confirmed the troubled plane's locator emergency device had emitted a distress signal.
It was mostly cloudy in the New Braunfels area shortly before the crash and there was a thunderstorm two hours later, the National Weather Service said.
Dan Dyer, president of the Amarillo Pickleball Club, said he'd played many games with four of the five people who died.
"I've handed them medals. They were excellent players. They were out to win some games," he said.
Dyer said a second plane was travelling to the event at the same time. Authorities confirmed it landed safely at the airport in New Braunfels, about 50km northeast of San Antonio.
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