Rescuers are combing through collapsed buildings in the southern Philippines after a powerful earthquake devastated coastal communities.At least 37 people have been killed and searches are underway for four people officially listed as missing.The Philippines Office of Civil Defence said collapsed and damaged buildings needed to be checked for possible survivors or people killed.The Philippines Coast Guard has deployed 150 responders, including search and rescue dogs, to help search for survivors.Rescue workers used dogs to look for trapped people at a collapsed grocery store. (Reuters/Noel Celis)"Most of the buildings are heavily devastated, there are so many collapsed buildings," Commodore Noemie Cayabyab told the ABC."The rescue teams mostly are conducting rescue operations … there are some possible trapped individuals."The magnitude-7.8 earthquake struck off the coast of the southern island of Mindanao early on Monday morning.The coastal city of General Santos and surrounding regions bore the brunt of the quake.According to an initial government assessment, about 2,000 homes and more than 100 government buildings and facilities had been damaged.Complex rescuePowerful aftershocks are complicating rescue and recovery efforts.The aftershocks being felt well into Tuesday evening."There's a lot of totally damaged and partially damaged houses," Kristin Roxas from aid agency World Vision Philippines said."There are children along the streets, living in outdoor tents."Authorities say 32,000 people have been displaced by the earthquake, with many now in emergency shelters.A rescuer prepares equipment for a search operation. (AP Photo/Basilio Sepe)"We are anticipating that number will rise," Faisah Ali from Save the Children Philippines said."Evacuation centres cannot accommodate everybody, we have seen families that are are staying outside."Also complicating matters are blackouts, damaged telecommunications networks, and damaged roads and bridges."We have heard from the communities during our assessment that they have no access to electricity, the internet and the network is currently down," Ms Ali said."There are also reports of landslides and damaged roads, so some families are currently isolated and they are asking for immediate support from the government and other actors to be able to restore back lifeline services."We are very concerned about the health of displaced children and their families."The Philippines Office of Civil Defence said at least 18 people were killed in a landslide that buried homes in the mountainside town of Glan.Aid agencies say accessing the town is too difficult at the moment because of the damage to roads and other infrastructure.The quake has destroyed crucial infrastructure such as bridges and roads, as well as buildings. (Supplied: GenSan DEV)The earthquake triggered tsunami fears, although only minor damage was reported after waves of up to 1.4-metres above tide-level were recorded.Schools and students affectedThe earthquake occurred at 7:37am on Monday, the first day back at school after the summer holidays.The earthquake levelled this building in General Santos. (Supplied: GenSan DEV)Children across thousands of schools were taking part in flag-raising ceremonies to mark the start of the term when the shaking began.Footage shows children hugging each other, staying low to the ground and praying for safety."The children are stressed and traumatised because of this earthquake," Ms Roxas saidThousands of public school buildings are being assessed to ensure they are not at risk of collapse.Philippines President Ferdinand Marcos Jr has sent senior officials from Manila to oversee search and rescue, reconstruction and relief efforts.ABC/wires