A Cuban airliner landed safely at Key West International Airport after six hijackers, some wielding knives, forced the crew to divert the flight from its original destination of Havana, U.S. authorities said.

The twin-engine Douglas DC-3, carrying 29 passengers, landed in Key West on Wednesday under U.S. military escort. Six hijackers surrendered to authorities, said FBI spokeswoman Judy Orihuela in Miami.

The six were expected to be arraigned Thursday on federal hijacking charges, Orihuela said.

"After they landed, the hijackers gave themselves up," airport manager Peter Horton said. "They surrendered their knives to airport police on the field."

The six crew members and 23 passengers, including five minors, disembarked safely and were interviewed by U.S. Customs agents, said Becky Herrin, a Monroe County sheriff's spokeswoman.

Orihuela said the passengers and crew would be processed and returned to Cuba. It was not known whether any had requested to remain in the United States.

The plane departed from Cuba and air traffic controllers at Miami International Airport spotted it on radar about 7:45 p.m. They were unable to make voice contact, said FAA spokeswoman Kathleen Bergen.

Air Force fighter jets scrambled from Homestead Air Force Reserve Base and a U.S. Customs Blackhawk helicopter escorted the blue and white plane to Key West, Bergen said. The plane landed safely at 8:06 p.m.

"The hijackers were separated fairly quickly from the passengers and crew. Everyone's OK," Herrin said. "Nobody tried ... anything."

The plane took off from Nueva Gerona, the principal city on the small Isle of Youth, according to Leonardo Pena, a Cuban civil aviation official.

Pena confirmed that the incident was being treated as a probable air piracy case. The plane was on a regularly scheduled flight from Nueva Gerona to Havana, he said.

Pena did not know who owned the plane, but Florida officials said it was owned by a company called Aerotaxi.

State-owned Cubana Airlines provides passenger service between Nueva Gerona and Havana, but it uses Soviet-era Antonov AN-24 planes.

The hijacking follows strained relations between the United States and the Communist-run island. Late Tuesday, the communist government announced the detentions of several dozen opponents and said U.S. diplomats may no longer move freely around the island.