Natural disasters, including a major earthquake and tsunami in 1918 and several hurricanes, as well as the Great Depression, impoverished the island during the first few decades under U.S. rule. Some political leaders, such as Pedro Albizu Campos, who led the Puerto Rican Nationalist Party, demanded a change in relations with the United States. He organized a protest at the University of Puerto Rico in 1935, in which four were killed by police.