MADRID, 13 March 2004 — Daily life ground to a halt across Spain yesterday as the nation observed a period of solemn silence to honor the 199 people killed in the Madrid train terror bombings.

Prime Minister Jose Maria Aznar pledged to hunt down those responsible for Thursday’s horrific, coordinated attacks — 10 bombs that blew up four trains in a 15-minute span — but said the massive investigation has not yet pinpointed who was responsible.

Interior Minister Angel Acebes said the armed Basque separatist group ETA remained the prime suspect, although suspicion has also fallen on Al-Qaeda.

But ETA yesterday denied responsibility for the attacks, a Basque newspaper said. The pro-Basque independence daily Gara, which ETA often uses to issue statements, told The Associated Press a caller claiming to represent the group phoned its newsroom to deny government allegations that ETA was behind the attacks.

As evening fell, hundreds of thousands of Spaniards gathered in Madrid and other cities for marches to protest the bombings. Italian Premier Silvio Berlusconi, French Prime Minister Jean-Pierre Raffarin, European Union President Romano Prodi and German Foreign Minister Joschka Fischer attended a massive rally. An estimated two million took part in the rally in Madrid.

Hospital officials said a 7-month-old baby girl died yesterday, raising the death toll to 199. The baby’s mother is apparently hospitalized and her father is missing. Earlier, a militant Basque politician denied ETA was involved and accused the government of lying to seek political advantage in tomorrow’s national elections. “The Spanish government is lying deliberately,” Arnaldo Otegi, leader of the banned Batasuna party, told reporters in the northern city of Bilbao.

If ETA is deemed responsible for Thursday’s attacks, that could boost support for Mariano Rajoy, Aznar’s hand-picked candidate to become Spain’s next leader. Both have supported a hard-line crackdown on the violent separatist group, which is fighting for an independent state in northern Spain, ruling out talks.

However, if Thursday’s bombing is seen by voters as the work of Al-Qaeda, that could draw voters’ attention to Aznar’s vastly unpopular decision to endorse the US-led invasion of Iraq and the deployment of Spanish troops.