The bodies of two Indonesians and one Myanmarese were pulled from the debris, while two other workers escaped with light injuries, officials said.
"Now the problem we are facing is we need to excavate a 35-metre heap of earth. We have deployed a K9 unit with three dogs to search for victims," Penang fire and rescue department director Saadon Mokhtar said.
Most of those trapped were believed to be foreign workers from Indonesia and Bangladesh, including Rohingyas, he said. One Malaysian, the construction site supervisor, was believed to be buried as well.