Boom!!
The whole place blew up violently. The formations that protected the house could not match up to whatever was thrown at the safe house and its environment.
When dust and smoke had settled down a little, everyone was seen to be in bad shape. Willow had burns everywhere and a concussion but apart from that, she was okay. She had cast a barrier over herself at the last moment with the little time the formations of the house had bought her.
All of Cole's limbs and his neck were hanging loosely at their joints. It was a mystery how he was still alive in that condition but then, he was still at death's door. Rose's body was a bloody mess and many of her body parts, including her head was missing. She died instantly. This was the same fate that Jack faced. He and Rose were already on the ship when the explosion happened. They both died instantly without any chance to fight for their lives.