Armed police have arrested a man near an entrance to the Houses of Parliament in Westminster.
Video from the scene shows a group of around a dozen officers surrounding a man, who was handcuffed after being Tasered inside the Carriage Gates.
Witnesses said the man had been pinned to the ground, with one police officer pointing a gun to the man’s head.
“Stop. Get down!” police shouted at the man, according to a Reuters photographer at the scene.
A pair of trainers in a clear plastic bag could be seen on the ground nearby.
The entrance where the incident happened was where unarmed PC Keith Palmer was fatally stabbed by Westminster attacker Khalid Masood in March 2017.
Security at the site has been beefed up since the atrocity, with a permanent armed presence now at the entrance.
However, it was not immediately clear whether the incident was terror-related as police were investigating.
The Metropolitan Police said the incident happened shortly before mid-day. The suspect was Tasered and arrested on suspicion of trespassing at a protected site, they said.
The House of Commons wrote on its Twitter feed: “We are aware of a situation outside the Palace of Westminster that was handled by the Met Police and is now over.”
The man was taken away in a police car at around 12.15pm.