The moment the bomb exploded was captured by a TV crew
A car bomb has exploded near the offices of a Basque television station in Bilbao in northern Spain.
The blast happened minutes after the building had been evacuated, following a warning call in the name of the Basque separatist group Eta.
Spanish media said there was structural damage to the building, but no casualties have been reported so far.
Eta's violent four-decade campaign for a sovereign Basque state has cost more than 800 lives.
A Basque police spokesman said Wednesday's blast near the Basque Radio-Television (EiTB) offices happened at 1105 (1005 GMT) and the area around the building had been evacuated and cordoned off.
The blast shattered the EiTB television building's windows
The explosion smashed the building's windows and left a thick pall of smoke hanging over the area.
The suspects are believed to have commandeered a car, because its owner was found tied up in the rural Arrigorriaga area near Bilbao.
Eta called off a ceasefire in June last year.
The Spanish government had already declared the peace process "finished" after a bomb blast by Eta killed two Ecuadorean men at a Madrid airport car park in December 2006.
Last month French police arrested the man believed to be the head of Eta's military operations, Miguel de Garikoitz Aspiazu Rubina, known as "Txeroki".
Spanish authorities accuse him of having ordered the attack on Madrid's Barajas airport.