Argentine television stations interrupted their broadcasts with news of Cabral's death [AP]

Argentine singer Facundo Cabral, a legend of Latin American folk music, has been shot dead in Guatemala City when unidentified gunmen riddled his car with bullets, authorities said.

Cabral, 74, and his driver were killed in the Guatemalan capital on their way to the airport at around 5am on Saturday, and at least one other person was seriously injured in the attack, police said. The shooting happened after Cabral finished performing a musical tour in the central American country.

"The vehicle was hit by 18 bullets," said Juan Manuel, a spokesman for Guatemalan President Alvaro Colom. Colom said he spoke to Argentine President Cristina Fernandez to express his condolences.

Argentine television stations interrupted their broadcasts with news of Cabral's death.

A firefighter at the scene said colleagues saw black vehicles pull up and open fire on Cabral's white Range Rover and the beige Chevrolet Tahoe accompanying the singer.

However, the motive for the shooting was not clear, authorities said.

Guatemala, one of the poorest countries in the region, has one of Latin America's highest murder rates.

Colom's office said in a statement that authorities were investigating whether the shooting of the singer was robbery-related or a targeted attack.

"We will find these criminals and bring them to justice," Colom told Argentine radio.

Argentina's Foreign Minister Hector Timerman paid tribute to Cabral on his Twitter account.

"The murder of Facundo Cabral in Guatemala brings us great sadness," he wrote. "Adios amigo!"

A large crowd of onlookers quickly gathered at the crime scene, which was next to a fire station a few hundred metres away from the turn-off for the airport. Some shouted angrily as police and army cordoned off a large stretch of the road.

"We want justice," cried one man.

Rise to stardom

Rising from humble origins, the outspoken Cabral was best known for his 1970 song "No Soy De Aqui, Ni Soy De Alla," (I'm Not From Here, I'm Not From There Either) which was covered by many other artists including Julio Iglesias.

Nearly blind, Cabral rose to fame in the 1970s as a protest singer and went into exile in Mexico during Argentina's 1976-1983 military dictatorship.

His songs later turned more spiritual and he continued to fill concert halls across Latin America.

Rigoberta Menchu, a leading activist for the rights of indigenous peoples in the country who won a Nobel Peace prize in 1992, said Cabral's murder was just one of many to afflict Guatemala.

"This is a well planned crime," she said. "International criminals base themselves in Guatemala because they know they can get away with acts like this," Menchu told reporters at the scene.