British Transport Police were called to Oxford Circus tube station, at around 10am this morning.
The Victoria line is suspended between Victoria and Warren Street whilst Police deal with the incident.
Transport for London (TfL) said on Twitter: “There are specialist BTP units on-site at Oxford Circus station.”
London Buses are accepting tickets via any reasonable route, TfL added.
Social media reports suggest a member of the public left their luggage at the Central London tube station sparking the incident.
It comes after a tube passenger was taken to hospital following reports of a stabbing on board the Jubilee line, British Transport Police (BTP) has said.
Officers were called to Green Park underground station in central London at 6.47pm on Friday, and a man has been arrested in connection with the incident.
Paramedics also attended and the passenger has been taken to a nearby hospital.
A passenger in his 30s, who was among those trapped in a carriage with the attacker, said he feared he would be “hacked to death underground”.
The witness, who did not want to be named, said: “All of a sudden there was a huge commotion.
“A man stood in the middle of the carriage and brandished a foot-long black machete.
“People started screaming, there was a stampede to the front carriage – people got trampled on and pushed into the plastic and stuff.”
The witness said he moved into the next carriage away from the attacker, adding that the victim had a wound on his head which he described as “a deep gash meaning the side of his head was hanging off”.
He added that the driver was unaware of anything happening for 10 minutes because the intercom was not working, and passengers were left defenceless on the moving Tube as the attacker “taunted” them.
“The attacker went back down the train. We heard screaming but we don’t know what happened,” he said.
“He then came back and stood at the opposite end of the carriage taunting us and making out he was going to break down the door of the carriage.
“It was completely and utterly terrifying. For about 10 minutes I genuinely thought I would be hacked to death underground.
“However, people showed compassion and care to each other – people held other’s hands, and a teenage boy saved his mum from being trampled.”
The witness said the Tube train eventually stopped and armed police arrested the attacker, who did not resist them.