The day after a vicious earthquake leveled apartment buildings, damaged hospitals and flattened an elementary school, Mexicans mobilized Wednesday for a massive rescue effort, digging in a frantic search for survivors.As the death toll reached 230 people, with 100 in Mexico City and the rest distributed in surrounding states, Mexicans confronted scenes out of parents' worst nightmares as rescuers pulled children's bodies from the ruins of the primary school.Butacross the capital, a surge of civic spirit took hold as thousands volunteered to provide medical care, food and water or to pick through buildings destroyed by Tuesday afternoon's quake, the second major temblor in the past month and the deadliest in three decades.In the central Roma neighborhood, small stores stayed open around the clock, offering food to rescue workers and families of victims. A hardware store lent tools to people trying to claw through massive pilesof debris.Inthe capital, the 7.1-magnitude quake caused more than three dozen buildings to crumple and damaged hundreds more, a north-south band of destruction that scarred poor and wealthy neighborhoods alike.Atleast 93 people died in the city, according to the coordinator of national civil defense, Luis Felipe Puente. That figure - and the overall death total of 223 as of late Wednesday afternoon - were reviseddownward slightly from earlier numbers released by the federal government."The priority continues to be rescuing people in collapsed structures and treating the wounded," President Enrique Peña Nieto wrote on Twitter on Wednesday, as he assessed damage in Mexico City and surrounding areas. Peña Nieto declared a three-day period of national mourning, the second time the government has made such a declaration this month.The latest quake knocked out power across 40 percent of this city of 20 million, and rescue and medical services were stretched to their limits.Authorities reported damage to at least 22 hospitals in and around Mexico City.One, in Morelos, collapsed completely. Some 5,000 schools were damaged by the quake.Tuesday's earthquake occurred exactly 32 years after Mexico's worst earthquake, which left thousands dead in 1985 and demolished entire neighborhoods in the capital.Mexico is particularly vulnerable to earthquakes: The country is in a region wherea number of tectonic plates butt up against one another, with huge amounts of energy waiting to be unleashed.