Spain says it has arrested five people in connection with Thursday's train bombings in Madrid that killed 200 people. Interior Minister Angel Acebes said at a Madrid news conference Saturday, that three Moroccans and two Indians have been taken into custody.

In addition to the five, he said two Spaniards of Hindu origin are being questioned, but are not expected to be arrested.

He said the suspects could be related to Moroccan extremist groups, adding police are continuing to investigate all possibilities.

Up until Saturday's announcement, the government had been saying the Basque separatist group ETA was the prime suspect in the attack. However it had also said authorities were investigating the possibility that Islamic extremists were responsible.

ETA has denied responsibility for the attack, while an Islamic group affiliated with the al-Qaida terror network, has claimed responsibility. Neither claim has been verified.

Sauturday, more than 1,000 people held a spontaneous demonstration outside the ruling party's headquarters in Madrid, demanding the government clarify who was behind the attack.

Debate over who is responsible could be a factor general elections Sunday, which will go on as scheduled even though the final days of campaigning were suspended despite the attack.

The ruling party has taken a tough stance against the Basque separatists. But it has also supported the U.S.-led war in Iraq, leading some to worry it that it could be a target of attacks by Islamic extremists.

Saturday's announcement of arrests comes at the end of a day in which funerals were held for many of the victims of Thursday's terrorist attack.