The glory of the Lord took the form of fire coming down from heaven and it burned up all the flesh on the altar. While the narrative makes clear that the sacrificial animals had already been placed on the altar, it would have taken some time for the process to complete. The divine fire caused the instantaneous consumption of the sacrificial animals.
24 Le feu sortit de devant l'Eternel, et consuma sur l'autel l'holocauste et les graisses. Tout le peuple le vit; et ils poussèrent des cris de joie, et se jetèrent sur leur face.