The mother, locally named Polina Titova, is said to have separated from her husband after police arrested her 35-year-old boyfriend as he tried to leave town.

A kindergarten teacher and four-year-old twins were found dead in her burnt down apartment after the blaze started to cover up their deaths, investigators said.

The mum, locally named Polina Titova, had recently split from her husband and had a new boyfriend, it has been learned.

Detectives have arrested a 35-year-old man believed to be the partner, Russian media report.

The 36-year-old man, from Kirovgrad in Sverdlovsk Oblast, was found dead by firefighters while fighting the blaze.

The bodies of her twins, who have not been named, were also found.

All three bodies were found covered in blood, according to reports.

Polina is said to have recently broken up with her unnamed husband.

Neighbors heard noises from across the wall the night they died, according to E1 news outlet.

Three engines and 10 firefighters rushed to put out the blaze, according to the Ministry of Emergency Situations.

Police reportedly set up roadblocks around town and arrested the new boyfriend as he tried to leave town.

It is currently unclear whether the suspect has been charged.

The investigation is ongoing.