Four small bombs have exploded at industrial sites in Spain's Basque region, injuring three people.
Police said the blasts came without any warning
Two policemen and a security guard were treated after inhaling toxic fumes at a chemical plant hit by one of the blasts, Spain's interior ministry said.
Local officials blamed the armed Basque separatist group, Eta, for the blasts.
The attacks came four days after Spanish Prime Minister Jose Luis Rodriguez Zapatero urged Eta to disband in his state of the nation address
The four devices went off in the space of about an hour starting at 0300 local time (0100 GMT) in the towns of Beasain, Bergara, Elgoibar and Soraluze, police said.
They said the blasts targeted two chemical plants, a paint factory and a metalworks facility.
Spain's anti-terrorism officials said no warning had been given about the attacks.
The Basque regional government said "all the data and the composition of the explosives point to Eta as being responsible", without giving further details.
Eta has been blamed for more than 800 deaths in its four-decade armed campaign for an independent homeland in northern Spain and south-western France.