MADRID, Spain (CNN) -- At least 173 people were killed and more than 600 injured in a series of explosions on Madrid's railway network at the height of morning rush hour, Spain's interior minister says.
Spanish officials are blaming the Basque separatist group ETA for the coordinated attack, which comes ahead of Sunday's general election.
Spanish Interior Minister Angel Acebes said there were a total of 13 explosions at the Santa Eugenia, El Pozo and Atocha stations. He said there was "no doubt" ETA was responsible.
The most deadly blast happened on a train entering Madrid's main Atocha station, Acebes said.
Security forces found other bombs, and detonated them in controlled explosions, he added.
Survivors described scenes of chaos and panic in the Spanish capital.
"The worst was people screaming for help inside the train and there was nothing we could do," one survivor told CNN+.
People in tears walked away from the city's main Atocha station in droves as rescue workers carried bodies away from the scene.
Many people with bloodied faces sat on curbs, using mobile phones to tell loved ones they were alive. (More eyewitness)
After the blasts, all political parties announced they were suspending campaign rallies ahead of Sunday's election, but there has been no word that elections would be suspended.
The government called for a three-day period of mourning and impromptu anti-ETA demonstrations have broken out in parts of Madrid.
So far, there has been no claim of responsibility.
ETA is listed as a terrorist organization by the United States and the European Union, of which Spain is a member.
Before Thursday's attack, ETA had been blamed for 800 deaths since it began its fight for an independent homeland in Spain's northern Basque region.
Spanish police -- who have foiled several recent bombing attempts by ETA -- were on high alert for terror attacks by the separatist group ahead of Sunday's vote.
Video of the scene showed the wreckage of the train at Atocha, broken into pieces by the force of the explosions.
Spanish radio SER reported the train -- arriving from the eastern Madrid suburb of Alcala de Henares -- was hit by three explosions, planted in plastic bags in the front, middle and rear cars.
Medical staff set up a field hospital to treat the wounded at the scene, and buses were mobilized to help ambulances transport the wounded to hospitals.
Survivors used mobile phones to tell relatives they were alive.
Shortly after the blasts, Basque leader Juan Jose Ibarretxe held a news conference from the Basque capital of Vitoria, condemning the violence and calling for demonstrations against ETA.
Basque Member of Parliament Gustavo Aristegui -- who was in Madrid at the time of the attack -- also blamed ETA for the attack.
"This is probably Spain's worst terrorist attack in history -- not probably, surely our worst terrorist attack ever," Aristegui told CNN.
"There are people that are real monsters that are trying to blackmail the whole society through acts of terror."
European Parliament President Pat Cox called the attack "the worst act of terror in the history of Spain and the worst act of terror in memory in any European Union state."
The attacks drew an immediate condemnation from British Foreign Secretary Jack Straw, who called it "a disgusting assault on the very principle of European democracy."
Spanish Foreign Minister Ana Palacio placed the blame squarely on ETA, saying "we knew they are preparing a very big terror attack."
"ETA has a very clear pattern in its activities and we unfortunately have a long experience in dealing with them," she said. (More reaction)
On February 29, Spanish police seized more than 1,000 pounds of explosives and arrested two suspected ETA members who were planning to carry out an imminent attack in Madrid, an official said.
CNN Madrid Bureau Chief Al Goodman contributed to this report.
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UPDATE: Spanish interior minister says new line of Madrid blast investigation opened after police find van with detonators and Arabic-language tapes.
PEACE
Spanish officials are blaming the Basque separatist group ETA for the coordinated attack, which comes ahead of Sunday's general election.
Spanish Interior Minister Angel Acebes said there were a total of 13 explosions at the Santa Eugenia, El Pozo and Atocha stations. He said there was "no doubt" ETA was responsible.
The most deadly blast happened on a train entering Madrid's main Atocha station, Acebes said.
Security forces found other bombs, and detonated them in controlled explosions, he added.
Survivors described scenes of chaos and panic in the Spanish capital.
"The worst was people screaming for help inside the train and there was nothing we could do," one survivor told CNN+.
People in tears walked away from the city's main Atocha station in droves as rescue workers carried bodies away from the scene.
Many people with bloodied faces sat on curbs, using mobile phones to tell loved ones they were alive. (More eyewitness)
After the blasts, all political parties announced they were suspending campaign rallies ahead of Sunday's election, but there has been no word that elections would be suspended.
The government called for a three-day period of mourning and impromptu anti-ETA demonstrations have broken out in parts of Madrid.
So far, there has been no claim of responsibility.
ETA is listed as a terrorist organization by the United States and the European Union, of which Spain is a member.
Before Thursday's attack, ETA had been blamed for 800 deaths since it began its fight for an independent homeland in Spain's northern Basque region.
Spanish police -- who have foiled several recent bombing attempts by ETA -- were on high alert for terror attacks by the separatist group ahead of Sunday's vote.
Video of the scene showed the wreckage of the train at Atocha, broken into pieces by the force of the explosions.
Spanish radio SER reported the train -- arriving from the eastern Madrid suburb of Alcala de Henares -- was hit by three explosions, planted in plastic bags in the front, middle and rear cars.
Medical staff set up a field hospital to treat the wounded at the scene, and buses were mobilized to help ambulances transport the wounded to hospitals.
Survivors used mobile phones to tell relatives they were alive.
Shortly after the blasts, Basque leader Juan Jose Ibarretxe held a news conference from the Basque capital of Vitoria, condemning the violence and calling for demonstrations against ETA.
Basque Member of Parliament Gustavo Aristegui -- who was in Madrid at the time of the attack -- also blamed ETA for the attack.
"This is probably Spain's worst terrorist attack in history -- not probably, surely our worst terrorist attack ever," Aristegui told CNN.
"There are people that are real monsters that are trying to blackmail the whole society through acts of terror."
European Parliament President Pat Cox called the attack "the worst act of terror in the history of Spain and the worst act of terror in memory in any European Union state."
The attacks drew an immediate condemnation from British Foreign Secretary Jack Straw, who called it "a disgusting assault on the very principle of European democracy."
Spanish Foreign Minister Ana Palacio placed the blame squarely on ETA, saying "we knew they are preparing a very big terror attack."
"ETA has a very clear pattern in its activities and we unfortunately have a long experience in dealing with them," she said. (More reaction)
On February 29, Spanish police seized more than 1,000 pounds of explosives and arrested two suspected ETA members who were planning to carry out an imminent attack in Madrid, an official said.
CNN Madrid Bureau Chief Al Goodman contributed to this report.
___________________
UPDATE: Spanish interior minister says new line of Madrid blast investigation opened after police find van with detonators and Arabic-language tapes.
PEACE
