A car bomb exploded at a police barracks in northern Spain’s Basque Country early on Wednesday, killing one person and wounding four, police said.

The bomb exploded in a Civil Guard barracks in the town of Legutiano just before 3 a.m. (0100 GMT), a Basque Country police spokeswoman said, and a police rescue team with dogs was used to search for people trapped in the rubble.

One person trapped under the wreckage died and the blast wounded four others, two men and two women.

There was no warning before the attack, which took place in an area that is often the target of Basque separatists. No one has claimed responsibility, police said.

The Basque separatist group ETA has killed more than 800 people in four decades of violent struggle for independence for the Basque Country, which lies in northern Spain and southwestern France.

ETA’s last fatal victim was a former small town politician for Spain’s governing Socialist Party, gunned down just before a national election in March, police said.