The accident occurred when the plane suddenly plunged to the ground at the end of the runway while on take-off, the club reported in a statement.
The players were on their way to Goiania, in the central region of the country, to play a match against Vila Nova.
Brazilian media reported that the players were travelling in a private plane because they had tested positive for Covid-19, that Sunday would be their last day of isolation, and the rest of the players would travel on a commercial flight.
The victims were identified as president Lucas Meira and players Lucas Praxedes, Guilherme Noé, Ranule and Marcus Molinari, as well as the pilot, who was named only as Wagner. There were no survivors, the club said.
Palmas Futebol e Regatas were founded in 1997 and play in Brazil's fourth division.
The cause of the accident was not immediately known.
Tocantins fire officials reported that the twin-engine Baron model had a capacity of six occupants. When firefighters arrived at the crash site, 500 meters from the runway, the aircraft was being consumed by fire. At least two explosions were registered, according to the official report.
The Brazilian Football Confederation expressed its solidarity with Palmas' family members and the club’s fans in an official note, and it ordered a minute of silence in all matches played on Sunday as a sign of mourning.
In 2016, a plane crash killed 19 players of the Chapecoense football club. Chapecoense’s plane went down en route to the club’s first-ever South American tournament final in Colombia after it ran out of fuel near Medellin.
“Unfortunately, we know what this moment of pain is like and we wish that no other group had to feel the same,” Chapecoense said in a statement. “You won’t go through this alone.”
Alejandro Domínguez, the president of South America's soccer body Conmebol, offered his condolences.
“I deeply regret the plane crash that affected Palmas," he said on Twitter. “My condolences to all those who make up the club, family and friends at this sad time.”