"Karlsruhe" then left Kristiansand on the evening of 9 April with three of the torpedo boats as escorts. The British submarine was positioned outside the fjord, and when her crew spotted the German ships, she fired a spread of torpedoes. "Karlsruhe" took evasive action, but one torpedo struck her on the starboard side amidships, blasting a large hole in the hull and allowing thousands of tons of water to flood in. The flooding disabled her engines and electrical generators, which cut off power to the pumps that were trying to keep pace with the incoming water. With those pumps inoperable, Rieve decided there was no hope of saving "Karlsruhe" and issued the order to abandon ship two hours after the attack. The torpedo boat took off her crew and fired two more torpedoes into "Karlsruhe" to scuttle her.