A Spanish policeman was shot after surprising several people apparently planting a bomb outside a police barracks in the town of Leitza near the Basque Country before dawn on Sunday, state news agency EFE said.
The suspects fled after the shooting and the police officer was treated for a bullet wound that fractured his arm, EFE said.
A government official confirmed a policeman had been shot in the arm but declined to give other details.
A bombing at barracks in the northern city of Burgos in July injured 65 people and was blamed on ETA rebels.
On Tuesday, police arrested 34 members of an outlawed youth group linked to ETA, which has killed more than 800 people in a 50-year struggle for Basque independence from Spain.
Polls suggest a majority of Basques might support independence but about 15% or fewer sympathise with the radicals associated with ETA.



