The warden of a maximum security prison in Guatemala was shot to death Wednesday on a highway east of this capital, authorities said.

Jose Vidal Sarceño Lemus, 48, the warden of the Fraijanes II prison, was driving in his car with a nephew when the vehicle was intercepted by the killers, a police spokesman told reporters.

"It was a direct attack because the shots were at him and the murderers then fled," he said.

Sarceño's nephew was not hurt.

The attack was carried out on the highway linking the town of Fraijanes with Guatemala City.

Sarceño, who had been the Fraijanes II warden for three months, did not have any special security measures in place and had not mentioned receiving any threats, prison service chief Edgar Camargo told the media.

"We have not been informed of ... any kind of threat and we're evaluating why this situation could have occurred," Camargo said.

The Fraijanes II prison houses some 50 suspected members of the feared Mara Salvatrucha gang.

Last week, inmates at Fraijanes II tried to stage a riot to protest searches of the cells made by guards, Camargo said. EFE