After a failed escape attempt to seize the notorious island prison’s boat launch, rioting prisoners took hostages and fortified themselves in one of the cell blocks. On 3 May 1946, prison authorities summoned assistance from nearby Treasure Island Naval Station and the US Army post at The Presidio. Two platoons of marines and coast guardsmen led by Gen Joe Stillwell and BG Frank Merrill arrived the next morning. Using tactics they learned fighting dug in Japanese; the marines and the prison guards isolated the prisoners from the hostages and then stormed the cell block. Three prisoners and two guards were killed, with about a dozen wounded. Two captured prisoners were eventually executed in the gas chamber.