Firefighters were searching through rubble Tuesday morning for four people feared buried in an explosion that collapsed a three-story apartment building on southern Frances Mediterranean coast. Authorities for the southern Var region said one person was pulled in critical condition from the building remains and three others required emergency medical treatment following the blast in the early hours of Tuesday morning in the coastal town of Sanary-sur-Mer, The Associated Press said. Four people remain unaccounted-for and are feared buried under the giant pile of debris, Var authorities said. The cause of the blast wasnt immediately clear but Var authorities said first responders noticed a strong smell of gas on arrival at the scene.