At 5:12 am on April 18, 1906, a major earthquake struck San Francisco and northern California. As buildings collapsed from the shaking, ruptured gas lines ignited fires that spread across the city and burned out of control for several days. With water mains out of service, the Presidio Artillery Corps attempted to contain the inferno by dynamiting blocks of buildings to create firebreaks. More than three-quarters of the city lay in ruins, including almost all of the downtown core. Contemporary accounts reported that 498 people lost their lives, though modern estimates put the number in the several thousands. More than half of the city's population of 400,000 was left homeless. Refugees settled temporarily in makeshift tent villages in Golden Gate Park, the Presidio, on the beaches, and elsewhere. Many fled permanently to the East Bay.