Brazilian police have arrested a man who allegedly shoved a Sao Paolo woman celebrating her 27th birthday in front of a train, in a shocking random attack that was caught on camera.

Maria da Conceicao Oliveira was catching a morning train at Se Station, the busiest metro stop in Brazil's largest city, when the attacker ran up behind her and pushed her onto the tracks.

She miraculously survived the impact but doctors at the Santa Casa Hospital, where she is currently receiving treatment, had to amputate her right arm to save her life.

The horrific attack was filmed by a camera set-up in the driver's cab.

Eyewitnesses said the assailant, who can be seen wearing a withe t-shirt in the video, ran away laughing from the scene.

The victim's sister said she was due to meet with da Conceicao later that day to celebrate her birthday.

Police said they've arrested a 33-year-old thanks to an anonymous tip-off.

The man's brother told detectives that the suspect, whose name has not been released by authorities, left their house in a hurry hours after the incident, taking 50 Relas (£19) with him.

"[He said] he had done something stupid," the brother said, G1 Globo television reported.

He realised what his brother had done only after watching the news on TV, he said.

The suspect is reportedly affected by schizophrenia and was known to police for having a record of at least another nine cases of assault.

"I want to look him in the eyes and ask him: 'why you did it?'" da Conceicao's mother, Maria das Neves Oliveira, said.

Her daughter is struggling to come to terms with the loss of a limb, but hopefully will recover soon, she said.

"It was her birthday and she won a new life. That's what is comforting me now."

Sao Paulo Woman Pushed In Front of Train
Brazilian woman Maria da Conceicao Oliveira was shoved in front of an approaching train at a Sao Paulo metro station Reuters