"We are treating this as a terrorist incident," Richard Walton, a commander with the Metropolitan Police Service Counter Terrorism Command, said in a release. "I would urge the public to remain calm, but alert and vigilant. The threat from terrorism remains at severe, which means that a terrorist attack is highly likely."

>> Read more trending stories

Police were called to the station around 7 p.m. The suspect was seen running through an exit and threatening other people with a knife, according to The Telegraph.

An officer used a Taser on the suspect and he was arrested around 7:14 p.m. He is being questioned by anti-terrorism detectives.