The single-engine turboprop's two Costa Rican pilots also died in the crash, President Luis Guillermo Solis Rivera said in a statement posted on social media
. There were no survivors.
Costa Rica's Ministry of Public Security posted several images of the wreckage on its official Facebook page, showing the plane engulfed in flames in a wooded area, with smoke billowing from charred rubble.
A spokesperson for the US State Department confirmed the deaths of "multiple US citizens" in the crash.
"We express our condolences to all those affected by this tragedy. We are in contact with Costa Rican aviation authorities and will continue to monitor the situation," the spokesperson said.
Hours before crash, winds forced change of course
It was not immediately clear what caused the crash, which happened early Sunday afternoon in Nandayure, a region in Costa Rica's Guanacaste province.
Authorities said Sunday they were focusing on recovering the victims' bodies and would begin an investigation into the cause of the crash first thing Monday.
The plane took off from the Punta Islita Airport at 12:10 p.m. Sunday, bound for Costa Rica's capital, San Jose. Officials received reports of the crash around 12:20 p.m., 10 minutes after takeoff, CNN affiliate Teletica reported
, citing civil aviation authorities.
Earlier Sunday, heavy winds had forced the plane's pilots to land at another airport and delay their arrival in Punta Islita, Teletica said.
President vows to help victims' families
Costa Rica's President expressed his condolences on Twitter.
"The government vows to do everything necessary to help the victims' family members in whatever they need in this difficult moment and sends them the solidarity of all the Costa Rican people," Solis said.
The private aircraft, a Cessna 208B Grand Caravan registered as TI-BEI, was part of Nature Air's fleet, officials said. Officials from the airline could not be immediately reached for comment.
The Caravan is a popular utility aircraft that's routinely used for carrying passengers or cargo. More than 2,500 have been built since the aircraft entered service in 1984, according to the Aviation Safety Network.
One of the pilots who died in the crash was the cousin of Costa Rican ex-President Laura Chinchilla, the former leader said on her Twitter account