Photos show the aftermath of an earthquake in the southern Philippines

Rescuers are searching ruined buildings in the southern Philippines to ensure no one was still trapped a day after the strongest earthquake to hit the country in a half-century killed at least 37 people and displaced more than 20,000. Only four people were considered missing on official records in the southern provinces near where the 7.8 magnitude quake struck Monday morning. However, the Office of Civil Defense acknowledged several collapsed and heavily damaged buildings must be thoroughly inspected for possible survivors or casualties. The earthquake was centered off Mindanao and displaced more than 20,000, most of whom fled to emergency shelters.