Villarreal president Fernando Roig condemned the action and apologised on behalf of the club.
In comments reported on the Villarreal website, he said: ``Villarreal deplores and condemns what happened. We are convinced that this is a person who is outside of Villarreal and has specifically come to harm the club.
``We are making all appropriate inquiries and hope to be able to identify as soon as possible to the perpetrator and come down on him with the full weight of the law.
``Such acts do not represent the fans of Villarreal. In any case, the club wants to apologise and to acknowledge the work of the security forces in the evacuation.''