Doctors treated patients in tents set up under a scorching Philippine sun on Tuesday — including helping a young mother give birth — as the death toll from a major earthquake that collapsed buildings and sparked tsunami warnings topped 40. Thousands remained displaced and more than 450 injured following the magnitude-7.8 quake that struck off the southern island of Mindanao on Monday, according to national and local disaster agencies, though only four people were now believed missing. In the hardest-hit Sarangani province, some areas remain accessible only by helicopter and fears of aftershocks were slowing rescue efforts, local officials told reporters at a Tuesday briefing.