One soldier told DZMM radio on Thursday that troops and miners clearing debris in the town of Real pulled a 50-year-old woman and three children from the building's cavernous basement, which was used as a chapel by a group of Christians.
The woman told rescuers there were about 20 survivors after the building collapsed on 29 November, Captain Gerry Sultana added.
Soldiers were working frantically to find the other survivors.
"We were digging through mud, concrete slabs and twisted iron bars when we heard faint voices and cries for help from below the ground," Sultana said.
"We never expected any survivors from the ruins. After three days of digging, we only found decomposing bodies."
Fears of disease
Nearly 1400 people are dead or missing after a typhoon and three tropical storms hit provinces east and north of Manila in a span of two weeks, unleashing mudslides and flashfloods.
Rescue teams are scrambling to get food, clean water and tents to at least 650,000 survivors. Fears of disease are running high due to lack of sanitation.
"They survived because of their faith. They prayed hard and God listened to them"
Captain Gerry Sultana
President Gloria Macapagal Arroyo called the discovery of the four survivors in Real a "miracle" and said rescuers hoped to reach the rest.
At least 100 people were believed to have been inside the two-storey building, with four managing to scramble out just after it collapsed. About 40 bodies have been found in the rubble.
Sultana said the woman and three children found on Thursday had no injuries but were very weak and "white as ash" after surviving on water dripping from the ceiling. They were taken to a military camp for medical attention.
"They survived because of their faith," he said. "They prayed hard and God listened to them."