"Rescuers found the body of a fourth worker and removed it. The search is continuing among the debris, where people may be still trapped," a police source told RIA Novosti on Thursday.
The fourth body was found on Wednesday evening, and the search continued through the night. Six search teams are working at the scene.
A part the six-storey 19th-century building collapsed on the corner of Starokonyushenny Lane and Old Arbat Street at around 3 p.m. (noon GMT) on Wednesday. No one lived in the building as it was undergoing restoration.
"The house was considered hazardous three years ago, and the residents were moved out," a local emergencies spokesman told RIA Novosti on Thursday.
He said the collapse may have been caused by safety rule violations during construction work, but that there was no threat of the building collapsing further.
Prosecutors have opened a criminal case against the company that was carrying out the building's reconstruction.
