By EMILY SHAPIRO

At least three people were injured in a stabbing at a London tube station tonight, a crime that is being treated as a "terrorist incident," according to police.

Police responded to reports of several stabbings at the Leytonstone Underground tube station, said the Metropolitan Police, where the suspect was "reportedly threatening other people with a knife."

A taser was discharged by an officer, said police, and a man was arrested and taken into custody.

The attack is being treated "as a terrorist incident," said Commander Richard Walton, who leads the Metropolitan Police's Counter Terrorism Command.

"I would urge the public to remain calm, but alert and vigilant," Walton said. "The threat from terrorism remains at severe, which means that a terrorist attack is highly likely."

Three people were injured in the attack, police said. One man suffered knife injuries that were said to be serious, but believed to be non-life-threatening, while two other people suffered minor injuries.

ABC News