Russian police arrested a woman working as a nanny on suspicion of murder after she was found parading around Moscow with the severed head of a child and threatening to blow herself up near a subway entrance on Monday.

A video published on YouTube, which has since been taken down, showed a woman wearing all black waving what appeared to be a child's head while shouting in Russian, "I'm a terrorist! I want your death!" and "Allahu Akbar" outside the Oktyabrskoe Pole Field station in northwest Moscow.

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It took authorities more than an hour to detain the woman, who has been put in psychiatric care so physicians can evaluate her mental state, Moscow's Investigative Committee said in a statement.

CCTV footage published by Kremlin-sponsored Sputnik News showed police officers tackling the woman as what appeared to be the head fell to the ground and rolled away.

Warning: The footage below may be disturbing to some viewers.

A criminal investigation was launched after police responded to an apartment fire at Narodnoye Opolcheniye Street in Moscow and discovered the body of a 3- or 4-year-old child, which showed signs a violent death, the Investigative Committee said.

"According to preliminary information, the child's nanny, a citizen of one of the Central Asian states born in 1977, waited for the parents and older child to leave the flat, and then, for reasons not established, murdered the infant, set fire to the flat and fled the scene," the Investigative Committee said.

A law enforcement source identified the nanny as Gyulchekhra Bobokulova, a 38-year-old woman from Uzbekistan, according to Russia's Moskovsky Komsomolets newspaper. LifeNews, a Russian tabloid known for digging up scoops because of its close ties with security services, reported that the victim was a 4-year-old girl named Nastya M, citing police.

Russian police officers secure the area near a subway station in Moscow on Feb. 29, 2016.

Police first approached the woman at the entrance to the metro station to check her documents. At that point, she took the severed head out of her bag and began shouting that she would blow herself up, according to LifeNews.

Russia has long feared terrorist attacks at the hands of Islamic extremists operating in the Caucasus region of the country. President Vladimir Putin has said publicly that about 2,000 Russians as many as 7,000 people from former Soviet countries are believed to be fighting with ISIS in Syria and Iraq.

Earlier this month, Russia's state security service detained seven people in the country's Ural mountain region who were believed to be plotting to carry out terrorist attacks in Moscow, St. Petersburg and the Ural region, The Associated Press reported.