The word “tenebrae” means darkness, and it represents the Divine Office prayers formerly said in the dark hours of the morning. In the Tenebrae, the Church mourns the passion and death of Jesus and urgers her children to return to God.
Candles are extinguished one after another, to signify Jesus’ apostles, whom He calls the light of the world, gradually leaving Him at His death. At the time of His death, the world was covered in complete darkness. The loud noise at the end signifies the earthquake which took place after Jesus’ death.