HELSINKI, April 4 (Xinhua) -- All three members of a family were killed in a house fire that broke out Tuesday night in Kotka, southern Finland.

When firefighters arrived on the scene, the detached wooden house which was built during WWII was completely destroyed, and the parents and their adult son had died, Finnish national broadcaster Yle reported on Wednesday.

Veli-Matti Heininen, chief of the local fire brigade, told Yle that it was unclear whether there was a functional smoke detector in the house.

"Apparently there wasn't, as the family members were unable to escape. None of them," he said, adding that a fire alarm might have given them time to flee from the fire.

The fire started somewhere in the downstairs and developed overwhelmingly, as the house was furnished with many synthetic and oil-based materials, such as cushions, pillows, duvets and rugs, which were burnt very rapidly, according to Heininen.

Police and firefighters are investigating the cause of the fire.