A 7.1 magnitude earthquake struck Mexico City on Tuesday afternoon and officials have said it has so far killed 225 people, including children who were in school at the time. From CNN:

“The priority now is continue rescuing those who are still trapped and provide medical attention to the injured,” President Enrique Peña Nieto said, calling Tuesday’s quake — the second to shake Mexico in 12 days — “a new national emergency.”

The 7.1 magnitude quake turned dozens of buildings in central Mexico into dust and debris, killing at least 225 people. It occurred at a depth of 51 kilometers (32 miles), which experts consider to be shallow. Shallow quakes tend to be more destructive.

“Unfortunately many people have lost their lives, including girls and boys in schools, buildings and houses. I want to express my condolences to those who lost a family member or a loved one. Mexico shares your grief,” Peña Nieto said.

According to Luis Felipe Puente, national coordinator of civil protection for the Interior Ministry, 94 of the deaths came in Mexico City, which, with an urban area of more than 21 million people, is one of the most populous cities in the Western Hemisphere.

There were also 71 deaths in Morelos state, 43 in Puebla state, 12 in the state of Mexico, four in Guerrero state and one in Oaxaca state, according to Puente’s tally. To provide some scope of the affected area, Oaxaca de Juarez, the capital of Oaxaca state, is almost 480 kilometers (300 miles) from Mexico City.

The country has declared three days of mourning for those killed in the quake, according to Mexico’s Secretary of Public Function.