A stabbing at the Leytonstone Underground Station in east London is being treated as a "terrorist incident," said the London police, according to the France 24. The stabbing occurred when a man started threatening people with a knife around 7 p.m. Saturday night, resulting in one person sustaining serious injuries in the attack. Two other victims were treated for minor wounds.

Witnesses at the scene claim the suspect yelled, "This is for Syria!"

"It looked like he was attacking people at random," said a witness who described the attacker as tall and black, wearing a black jacket and headscarf.

Police arrived and used a stun gun to subdue the suspect before placing 29-year-old Muhaydin Mire under arrest, according to Time.

A video of the stabbing by a witness has gone viral. The London police are asking if anyone has more videos, pictures or information to please contact them.

"We are treating this as a terrorist incident. I would urge the public to remain calm, but alert and vigilant," said Commander Richard Walton, who leads the London police counter-terrorism unit, according to FOX News. "The threat from terrorism remains at severe, which means that a terrorist attack is highly likely."