A five-storeyed building under construction caved in Saturday afternoon at coastal town Canacona, 80 km from here, trapping the on-site labourers.
Bodies of 14 people were retrieved from the rubble since Saturday, and one more body was found Sunday, according to officials.
The Pune-based National Disaster Response Force (NDRF) team, which arrived Sunday, also was lending a helping hand in rescue operations.
An official supervising the rescue effort told reporters that it was not possible to know how many people were still trapped under the debris, because the building contractor and site engineer who maintained the attendance records were missing.
Acting South Goa Collector Venancio Furtado said: "We do not know how many (people) exactly. But there was shouting and screaming from inside yesterday (Saturday) which suggested that there are around 20 persons still inside. The number is unconfirmed."
The district official said the sounds came from a large cavity within the rubble, which was caused after a slab fell horizontally on some girders, creating a space within.
But reaching out to the workers is tricky as the concrete slab was threatening to cave in the moment rescue team made efforts to reach out to the victims, he said.
"They (rescue team) are using gas cutters and other machines, but reaching to those trapped inside is not easy," Goa Chief Minister Manohar Parrikar, who was personally monitoring the rescue efforts, said.
Fear has now gripped the few occupants of a building adjoining the Ruby Residency complex - the accident site - as the impact caused by the collapse has developed cracks in it.
Efforts to contact the real estate development company - which constructed the complex - failed as the phone number listed on its official website is switched off.
The contractor as well as the company's directors are untraceable, police said
--IANS (Posted on 05-01-2014)