Suspect Dhamaka Singh- Detective Riddle

After several crimes had been committed in the city, the police decided to visit the main suspect Dhamaka Singh. He lived in the countryside. When the officers entered the house, they found no one inside. They searched the entire place including the attic which was a mess. Then they decided to wait for the house owner to come home. One of the police officers went to buy some water. When he came back he told the rest of his colleagues there was no need to wait anymore. Why?

The attic of the window was closed when the police arrived, but now it's open. Dhamaka Singh escaped through the window. The attic of the window was closed when the police arrived, but now it's open. Dhamaka Singh escaped through the window.