The small plane's pilot was approaching the remote town in heavy rain, with low visibility, and appeared to inadvertently start landing halfway down the runway, Amazonas state security secretary Vinicius Almeida told a news conference.
The plane ran out of landing strip and crashed, killing all 12 passengers and two crew, he said.
Initial investigations indicated the passengers were all Brazilian men traveling to the region for sport fishing, the state government said in a statement.
"Our teams have been on the ground responding since the moment of the crash to provide the necessary support," Governor Wilson Lima wrote on X, formerly known as Twitter.
"My solidarity and prayers to the victims' family and friends."
Media reports showed the small white plane belly-down on a dirt track, its front end crumpled into the dense vegetation to the side.
The plane was an EMB-110, a twin-engine turboprop manufactured by Brazilian aircraft-maker Embraer.
It was on its way from the state capital, Manaus, to Barcelos, about a 90-minute flight.
Officials said two aircraft approaching Barcelos around the same time had returned to Manaus because of the weather.
News site G1 said locals living near the airport were the first to arrive at the scene, helping emergency workers remove the victims' bodies from the plane.
TV footage showed people gathered around the crash site, many standing under umbrellas in the rain as emergency workers sorted through the mangled fuselage.
The Brazilian air force and police will investigate the crash, authorities said, adding that many details were still unclear.
Initial news reports had said US nationals were believed to be on the plane, but Amazonas officials said preliminary investigations indicated all the victims were Brazilian.
Sport fishing paradise
Officials said the victims' bodies would be taken to the state capital Sunday to be identified.
Traveling sooner was impossible as take-offs and landings at night are not permitted in the region, they said.
"An air force aircraft will leave Manaus tomorrow around 5:00 am" with investigators and emergency officials, said Almeida.
"The expectation is that tomorrow we'll be able to bring the bodies to Manaus and immediately take them for forensics and then release them to the families."
Located on the Rio Negro, an Amazon tributary, Barcelos borders several national parks and other protected areas.
This is peak season for fishing in the region, a popular spot for catching tropical river species such as the "tucunare," or peacock bass.
Covered mostly in dense rainforest, Amazonas is an adventure travel destination. It receives hundreds of thousands of visitors each year, according to Amazonastur, the state tourism company.
© 2023 AFP