On the north side of the atoll, the 4th Marine Division followed a similar plan, first capturing islets Ivan, Jacob, Albert, Allen, and Abraham on 31 January, and then landing on Roi-Namur on 1 February. The airfield on the western half (Roi) was captured quickly, and the eastern half (Namur) fell the next day. The worst setback came when a Marine demolition team threw a satchel charge of high explosives into a Japanese bunker, not realizing it was a torpedo warhead magazine. The resulting explosion killed twenty Marines and wounded dozens more and caused an observation pilot to radio, "The whole damn island has blown up!"