"At the time of the explosion, her apartment at 10, Bolshoi Gnezdnikovski pereulok, was empty. In official information, nobody has been registered in the apartment since 2000 and neighbours say it has been empty for a long time", a GUVD spokesman told RIA Novosti.
Tregubova has not turned to the police since the explosion, he said.
The information was confirmed to RIA Novosti by the Tverskoi police station, whose officers were the first to arrive to the site.
Journalist Yelena Tregubova has told some media that the explosion sounded on the staircase when she was about to leave her apartment.
According to the GUVD, a self-made non-fragmentation bomb of 50-100 grams TNT was triggered at the door of apartment 222 on the second floor at 14:00, Moscow time. The blast damaged the entrance door. Reported no victims.
Earlier, journalist Tregubova worked for metropolitan newspapers, such as Izvestia and Commersant.
