Argentine singer Facundo Cabral, one of the stars of Latin American folk music, was shot dead in Guatemala City early on Saturday when gunmen riddled his car with bullets, authorities said.
Cabral, who rose to fame in the 1970s as a protest singer, was on his way to the airport when three vehicles boxed in his white Range Rover and opened fire, killing him and injuring his driver, Guatemala's Interior Minister Carlos Menocal said.
Police earlier said the driver was killed.
Born to a poor family in 1937, 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.
Cabral 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. He had been in the Central American country on tour.
Argentine television stations interrupted their broadcasts with news of the 74-year-old singer's death.
Guatemalan president Alvaro Colom vowed swift action.
"We will find these criminals and bring them to justice," he told Argentine radio.
Colom said he spoke to Argentine President Cristina Fernandez to offer his condolences for the killing, the motive for which was unclear. Guatemala, one of the region's poorest countries, has one of Latin America's highest murder rates.
Guatemalan authorities said the gunmen peppered Cabral's car with 18 bullets in an exchange of fire with the singer's security detail, which was in a separate vehicle.
His driver, businessman Henry Farina, was injured, along with one person from Cabral's security detail. Enrique Vaca Narvaja, Argentina's consul to Guatemala, told Argentine television Farina may also have been a target.
Cabral was mourned by fans across Latin America. Argentine Foreign Minister Hector Timerman paid tribute to the singer.
"The murder of Facundo Cabral in Guatemala brings us great sadness," he wrote on his Twitter account. "Adios amigo!"
Venezuelan President Hugo Chavez followed suit: "We are weeping with Argentina."
Edgar Palacios, 54, a fan in Guatemala City, said the singer would not be forgotten.
"Facundo Cabral died but his music will never die, just like John Lennon died but his music never died," he said. "Cabral wasn't just from one country. He was a universal man."
Guatemala has been racked by incursions from Mexican drug gangs, notably the brutal Zetas cartel.
Colom has struggled to contain the violence and Cabral's murder is an embarrassment to the president just two months before a first round of presidential elections which polls show his center-left National Union of Hope party (UNE) may lose. Colom himself is barred by law from seeking re-election.