Madrid, Nov 28 (IANS): Three people were killed and three seriously injured in an explosion in a factory in Ibi, a town in southeastern Spain.

Spanish government delegate for the region of Valencia Pilar Bernabe confirmed the deaths in the blast on Wednesday at the Industrias Climber factory in Ibi, around 35 km from Alicante, Xinhua news agency reported.

Bernabe said that 39 people were in the building when the explosion happened at around midday, causing the roof and part of the walls of the building to collapse and trapping several people under the debris.

As well as the deceased, three people were seriously injured by the explosion and have been taken to nearby hospitals in Alicante, Valencia and Alcoy. Meanwhile, a large rescue operation involving seven fire engines, seven ambulances, a medical helicopter and local police has been launched.

Three more people suffered minor injuries in the blast.

The mayor of Ibi Sergio Carrasco said two victims were from his town and the third from nearby Xixona. He said the three were "young people," and announced a period of official mourning.

Authorities have opened an investigation into the cause of the explosion, with the first hypothesis being that a boiler exploded.

Industrias Climber specialises in packaging for food production, such as expanded polystyrene, and according to Spanish media has not suffered any safety incidents in the past.