Smoke and flames rise from a car following an explosion in the Palmanova beach area, southwest of the island's capital, Palma de Mallorca, Spain, on Thursday, July 30, 2009. The explosion may have been caused by a bomb attached to the underside of a police patrol vehicle, killing two officers a day after another car bombing blamed on Basque separatist group ETA destroyed a police barracks in the northern city of Burgos. (AP Photo/ Liam Oliver) ** UNITED KINGDOM OUT SPAIN OUT TV OUT **
PALMA DE MALLORCA, Balearic Islands (AP) -- The leaders of Spain's main political parties paid tribute to two slain police officers Friday as security forces guarded against a fresh attack on the 50th anniversary of the founding of the armed Basque group ETA.
Authorities blame ETA for an explosion that killed the officers near a police barracks on Mallorca island Thursday and a car bomb that wounded more than 60 people in the northern city of Burgos on Wednesday.
The Interior Ministry's represent in Mallorca, Ramon Socias, told reporters police "were still working on the hypothesis that the terrorists had not abandoned the island and were holed up in an apartment waiting for the situation to cool down a bit so that they can get out."
The ministry issued photographs of six suspected ETA members and called on the public to help track them down. The ministry did not say whether it suspected any of the six played a role in the attacks.
Spanish National Radio said police were looking for two Basque youths seen in Palma de Mallorca this week as police stepped up security prior to the annual visit of the royal family to their summer residence at Marivent palace, some six miles (10 kilometers) from where Thursday's bomb went off.
King Juan Carlos is due to arrive on the island this week.
The radio said that the Basque youths had rented an apartment in Palma but had not been seen since the attacks.
Prime Minister Jose Luis Rodriguez Zapatero flew to Mallorca early Friday with Popular Party leader Mariano Rajoy and placed medals of honor on the coffins of the officers, both members of the paramilitary Civil Guard in charge of policing rural areas and guarding official buildings.
Bells tolled at noon as people gathered in silence for five minutes outside town halls across Spain in pay their respects. Crown Prince Felipe, Princess Letizia and other authorities attended a funeral Mass at the Cathedral in Palma de Mallorca and later expressed their condolences to the relatives of the dead officers.
ETA was founded on July 31, 1959, and has killed more than 825 people since beginning its violent campaign for an independent Basque state in 1968.
If confirmed as ETA attacks, the blasts would conflict with government assertions that the group is seriously weakened after major police crackdowns in Spain and France in recent years. Their timing, two days before the milestone anniversary, may be part of an ETA effort to demonstrate it is in no danger of breaking up.
ETA is now blamed for nine attacks this year.
"The government has given orders to the security forces to be on maximum alert, to double their work, to increase even more their efforts and to protect themselves from these vile murderers," Zapatero said late Thursday.
In Madrid, armed police patrolled the streets around the headquarters of the country's two main political parities, the governing Socialists and the conservative Popular Party.
Several people were also lightly wounded in Thursday's bombing in the Palmanova beach resort area, southwest of the island's capital.
The explosion, caused by a bomb attached to the underneath of a vehicle, occurred at the height of the summer holiday season for the Mediterranean island resort, which is one of Europe's main tourist destinations.
"I was asleep outside the pool. Next thing I heard was the biggest explosion I've heard in my life," English tourist Michael Edgware told Associated Press Television News.
"I woke up and I thought 'what's going on?" he said, adding "Then I looked out and I saw fire, flames and fire brigades putting fires out. I got a bit scared."
Officials shut down the island's airports and ports for several hours while police searched for bombing suspects. Strict airport, road and boat controls were also being applied Friday.
Hours after the blast, police found another bomb attached to a police car in the same area and were forced to carry out a controlled explosion.
The attack Wednesday morning on the Spanish mainland also targeted a police compound and surrounding buildings, in which around 120 people including dozens of children were at the time of the blast. More than 60 people were reported injured.
There were no warning calls before the two attacks, for which no group has claimed responsibility.
Zapatero said the attacks were staged as Spanish police in collaboration with French counterparts were hitting ETA hard "dismantling its organization, thwarting its action, identifying its members and detaining them more rapidly each time and in greater numbers."
Spain has vowed to crush the separatist group since ETA ended what it had said was a permanent cease-fire with a 2006 bombing that destroyed a Madrid airport parking garage and killed two people.
Associated Press Writer Ciaran Giles in Madrid and APTV cameraman Hernan Munoz contributed to this report.
(This version CORRECTS spelling of princess' name to Letizia)
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