Four bombs have exploded at popular seaside resorts in Cantabria, northern Spain, after warning calls from the Basque separatist group ETA.
There were no casualties after the authorities evacuated the areas in response to the warning.
The first bomb exploded on a seafront promenade in Laredo, one of northern Spain's most popular holiday destinations, damaging the walkway, breaking windows and sending a 25m plume of smoke into the air.
Holidaymakers had been cleared from the beach 45 minutes earlier and took cover in local cafes and bars, which drew down shutters to protect against the blast.
The second bomb went off in dunes at Noja, about 30km from Laredo, causing a loud blast but no damage.
Poor weather meant there were few people on the Noja beach but a police call to evacuate the area sent tourists running, blocking the road out of town to the city of Bilbao. The third explosion was in Laredo, again causing no injuries. The fourth hit in Noja.
The explosions marked the beginning of ETA's traditional summer bombing campaign in which it targets Spanish holiday resorts as part of its four-decade struggle for an independent Basque state in northern Spain and southern France.
ETA (Euskadi ta Askatasuna, or Basque Country and Freedom) is listed as a terrorist organisation by Spain, the US and the EU.
It has killed more than 800 people since 1968, typically with car bombs or shootings. More than 750 suspected ETA members have been detained since 2000.
The Cantabria blasts were the first attributed to ETA since 14 May when the separatists exploded a bomb without warning at the Civil Guard barracks in Legutiano, killing policeman Juan Manuel Pinuel-Villalon and injuring four others.
