Basque separatists blamed for Madrid blasts
Explosions slightly injure six and cause massive traffic jams
MADRID, Spain (CNN) -- Five explosions hit gas stations in outlying areas of Madrid as residents streamed out of the city Friday evening ahead of two holidays.
Six people were slightly injured at two locations, including two police officers whose eardrums were hurt, said Interior Minister Jose Antonio Alonso.
Alonso said the blasts apparently were the work of the Basque separatist group ETA, in whose name a warning was issued about one hour before the bombs went off. The preliminary probe also pointed to ETA, the official said.
Police described the bombs as low-potency and stashed in trash cans or some other container.
The explosions caused massive traffic jams ahead of the Constitution Day holiday and a Roman Catholic holy day.
Alonso asked Madrid residents to be calm but on the lookout for terror threats.
Authorities recently arrested top ETA leaders in France and seized huge caches of weapons and ammunition in raids.
Because of the crackdown, the Spanish government had led the public to believe that ETA was weakening.
Gorka Knorr, a senior Basque politician, said ETA wanted "to send a message of 'Here we are. We wanted to talk,'" Reuters news agency reported.
ETA, which has been blamed for more than 800 deaths in Spain since the 1960s, is designated a terrorist group by the United States and the European Union.
The bombs went off at stations along major highways on the northwest and eastern flanks of the capital: on National Highway 5 leading to Lisbon, Highway 6 to northwest Spain, Highway 607 to middle class and affluent parts of the city, Highway 3 to the Mediterranean city of Valencia and the M-42 Highway to Toledo.
All but one road had reopened Friday night.
Before the explosions, someone called the Basque newspaper Gara and said, "I'm warning you in the name of ETA," and said the bombs would go off at 6:30 p.m.
The newspaper put the warning on its Web site. ETA claims of responsibility usually are given to Gara.
The bombings of commuter trains in Madrid in March that killed 191 people and injured 1,500 were initially blamed on ETA, but authorities later concluded they were carried out by Islamic extremists with links to al Qaeda.
CNN's Al Goodman in Madrid contributed to this report
contributed to this report.