The partial collapse of the two-storey 20-room building in Soi Ramkhamhaeng 39 in Wang Thong Lang district took place at about 10.20pm and caused two slight injuries.

It also caused a short circuit, prompting officials to cut power to the premises.

A tenant of the building, Somboon Doklang, said she had heard concrete creaking at about 11am on Tuesday when workers were drilling concrete to lay pipes and then she left for work.

She returned that night and saw the building had sunk about a metre sunken and its walls had cracks in them, so she alerted authorities.

Wang Thong Lang District Office director Jitlada Thanomsak said the 20-year-old building was located on an old rice field, so its partial collapse may have stemmed from soil subsidence.

Jitlada said officials had aided tenants by providing them temporary shelter, as residents were barred from entering the building while the incident was inspected.

Metropolitan Police Area 4 chief Maj-General Nanthachat Supamongkol said no charges had been filed at this stage, pending the result of the probe.

The building has 33 tenants but only 19 had no place to stay after the incident. Of the 19, 10 will stay at police flats and the rest at a nearby community centre.