The emergency services in Seville have taken to social network sites to appeal for information, together with pictures and videos, so they can piece together what happened in the early hours of this morning.
They have stated that the eight people arrested are not of Arabic origin as reported on local sites, but said they are due to appear before the courts later today.
Red Cross workers had to treat at least a dozen injured as the six Easter parades with religious leaders and floats, known as the Madrugada, made their way through the centre.
It is believed there could have been four different incidents which somehow led to mass panic and a stampede in which people were knocked to the ground and trodden on. A similar incident happened in the year 2000.
Holy Week in Seville attracts hundreds of thousands of people, including tourists from around the world.
The Easter processions began at midnight but the disturbances first broke out near a bridge at around 4am today.
The eight people arrested are said to be known to the police and it could have been an orchestrated attempt to maliciously provoke a stampede.
Police arrested eight people after a stampede left at least 12 people injured
Everything started with a very loud noise
As in the Marbella incident, many people thought it was a terrorist attack with a lorry aiming at the crowds which was not the case.
However, the rumours, together with shouting, public disorder and threats, caused the crowd to run away and create a major problem for organisers who tried to calm the situation.
One witness told Spanish newspaper El Mundo: "Everything started with a very loud noise, it's the same thing that happened in 2000.
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"It's as if many animals were on a stampede. One side to another without a fixed course.Some ran in one direction and others in the opposite."
Another said: "It was like an earthquake."
Emergency services have taken to social media to appeal for information following the incident
A police spokesman said they were looking at images of the parade but at this stage felt there was no connection between the "isolated" four incidents.
"It is believed to be hooliganism and vandalism," said a spokesman.
The National Police have asked spectators who took videos on their phones to hand them in as evidence, with anonymity guaranteed.
A number of musical groups were unable to continue in the parade because of injuries received and damages to their instruments.
It has been revealed that the eight people arrested were not of Arabic origin as reported locally
"We have cancelled our involvement because of injuries and loss or damage to our instruments," said the Band of San Juan Evangelista on its Facebook site today.
This morning, the Seville emergency services issued a statement which said the panic incidents happened at different places at around 4am.
"From the outset, the police and health care system focused on trying to spread calm and control the situation while trying to identify the causes of what happened," they said.
"The investigations are still open and during the morning four police raids have been carried out with a total of eight people arrested who will be brought to justice for public disorder.
"These are isolated facts and without apparent connection and correspond with cases of vandalism and hooliganism."
"Three of the detainees who were shouting and beating are common criminals. One of them has had 36 arrests."
"It is believed the isolated incidents caused a domino effect and caused panic in various parts of the city.
"Data is now being collected from the various health services in order to be able to report the number of people affected."
The local council has praised the emergency services for its good work during the night in bringing calm back to the city and avoiding a tragedy.