Two Guatemalans, Elgin Vargas and Wilfred Stokes, were arrested by police investigating the killing.
Cabral's music promoter Henry Farina, a Nicaraguan who owns a chain of strip clubs, was believed to be the target of the attack, according to Carlos Menocal, Guatemala's Interior Minister.
Farina, who was driving the car at the time of the shooting, was badly injured and remains in a critical condition in hospital.
"One (of the killers) is the head of a band of assassins," Attorney General Claudia Paz told reporters. "He put together this group to commit murders."
The two men were allegedly caught on tape by security cameras at Cabral's hotel and also along the highway on the way to the airport.
