Panaji, Jan 5 (PTI): Over 20 people could still be under the rubble of the building that collapsed at Cancona near here but the possibility of finding more survivors at the site appears bleak as a huge pile of debris is affecting the pace of rescue operations.

Thirteen people were killed when an under-construction five-storey residential building caved in Cancona town yesterday.

Personnel of Goa fire and emergency services and Army carried out rescue operations overnight to look for more survivors but as 17 hours have passed since the mishap and due to huge pile of debris, the chances of finding anybody alive is getting slimmer with the passage of time.

Fire personnel fear that over 20 people could still be lying under the rubble and chances of anyone of them coming out alive was remote.

According to medical officials present at the site, out of 25 people--mostly labourers--pulled out so far 13 are declared dead.

"The rescue work is on. We can see three more completely bodies inside but to reach to them is difficult," a fire services official present at the site told PTI.

"The death toll is going to rise further as rescue operation proceeds," he said, adding the possibility of finding more survivors is remote.

"Earlier there were some sounds coming from the debris which helped rescuers to locate them and rescue two persons who were asking for help," said an eyewitness, adding no more voices are heard now from inside.

Officials said the building was being developed by Navi Mumbai-based Bharat Realtors and Developers.

Fire services officials said the rescue work will resume later in the day after the debris is cleared.

The marshy land around the site of collapse is also proving to be a hindrance for rescuers as one of the earth-movers at the site got stuck in mud.

A senior police official said keeping crowd of onlookers at bay is posing a challenge for them.