Quote:Television footage showed several men approaching and overpowering the woman, who some media reported suffered mental health problems.
"Monstrous and inexplicable," tweeted Russia's children's rights commissioner Pavel Astakhov, urging parents to carefully check on the mental state of nannies when they are hired.
Investigators said a nanny had been detained after the body of a child aged three or four years with "signs of violent death" was found on Monday in an apartment in northwest Moscow.
"According to preliminary information, the child's nanny... waited until the parents left the apartment with their elder child and, guided by unknown motives, killed the little one, set the apartment on fire and left the scene," the Investigative Committee said.
Some scary stuff going on around the world. Stay safe guys