Police and rescue workers search through the rubbles of a collapsed building in Pathumthani province, central Thailand, Monday. Pic: AP.

BANGKOK (AP) — A six-story building under construction on the outskirts of Thailand’s capital collapsed Monday, killing three workers and trapping at least seven others underneath the rubble, police said.

Emergency teams rescued seven people from the site and were trying to free the rest, police Maj. Gen. Smithi Mookdasanit said.

Smithi said there were about 30 workers in the area at the time of the collapse. It was unclear what caused the accident.

The building, located just north of Bangkok in neighboring Pathumthani province, was to be a dormitory for a local vocational college.