Police on Wednesday said up to 16 people were believed to have died when a building caved in during construction, as they issued arrest warrants for several people behind the project.
Three bodies -- including those of a woman and her four-year-old daughter -- have so far been retrieved from the rubble of an unfinished student accommodation block, which collapsed on Monday in Pathum Thani province, neighbouring Bangkok.
Rescuers on Tuesday pulled a 24-year-old Thai man alive from the debris, but police said they believed 13 other people had perished.
"Thirteen people are trapped in the debris -- 10 Thais and three Cambodians -- among them, there may be children," district deputy police commander Kritsadaporn Panprong said, explaining the children may have accompanied their parents who were working at the building site.
"They (the 13) are all likely to be dead," he said after sniffer dogs failed to find signs of survivors.
Police have arrest warrants for two project engineers, the site foreman, and the owners of both the construction company and the accommodation block, he added.
Labour groups have warned about lax safety standards and low wages at Thai construction sites, especially for migrant workers from Myanmar, Cambodia and Laos, who are often paid below the country's minimum wage.
The nation has seen a building boom in recent years as the property market has soared.