Close to 200 people have been killed in bombings on passenger trains in Madrid, Spain, in one of the worst terrorist attacks in Western Europe in years. No group has claimed responsibility for the explosions, which injured at least 600 and came three days before Spain is due to hold parliamentary elections.

On Thursday morning, the Spanish capital Madrid was rocked by a series of explosions on packed passenger trains and stations. Witnesses describe train cars being cut open like tin cans and horrific scenes of body parts scattered by the powerful force of the blasts.

The Spanish government is calling this the worst terrorist attack in its history and says it is the work of Basque separatists. After an emergency cabinet meeting, Prime Minister Jose Maria Aznar described the bombings as mass murder, vowing to hunt down those responsible. Speaking on nationwide television he urged Spaniards to stand firm in the face of terrorists.

No group has claimed responsibility for the blast. In Washington, President Bush called Prime Minister Aznar to express his condolences, while at the United Nations, Secretary General Kofi Annan expressed his shock.

"Regardless of how one defines terrorism, it is clear to all that the killing of innocent lives is terrorism and there's no arguments about it," said Mr. Annan. "It's morally unacceptable."

No arrests have been reported in connection with the bombings. While Spain is blaming Basque terrorists, some terrorism experts including M.J. Gohel of the Asia Pacific Foundation are not convinced.

"None of them have been known to be able to perpetrate this kind of sophisticated, simultaneous bombing to inflict mass casualties, which are the hallmarks, the fingerprints of al-Qaida," he said.

U.S. officials tell VOA that while the bombings have characteristics associated with previous acts of Basque terrorists, they also bear a resemblance to the kind of attacks al-Qaida is known for - pointing out that this attack involved multiple, coordinated blasts - one of the hallmarks of al-Qaida. The officials also say Basque separatists often give advance warning of an attack and in this case, Spanish officials say there were none.