A fire breaks out at an apartment building in central Moscow, Russia, on Feb 4, 2019. [Photo/VCG]

MOSCOW -- The death toll in a fire in a luxury apartment building in central Moscow has risen to six, the Russian Investigative Committee said Monday in a statement.

The committee has opened a criminal case on the grounds of negligence causing death of two or more persons, the statement said.

It did not mention any injury.

Earlier in the day, the Moscow division of the Russian Emergencies Ministry said four people were killed in the fire and two others were injured.

The fire broke out at 0:55 am Monday (2155 Sunday GMT) in an apartment on the fifth floor of the seven-floor building, the ministry said in a statement.

The operation involved 25 units of equipment including 12 water trucks and five lifting mechanisms, as well as 80 people, and lasted more than four hours because the fire was spreading fast in the house built in 1914 with wooden beams, it said.

Firefighters evacuated 42 people including eight children from the building, the ministry said.