A man was stabbed in front of the Home Office in central London.
The injuries of the victim should not put his life in danger, said the metropolitan police.
Officers were called in the building on Marsham Street, near Parliament, Westminster, at 1:06 pm MST. A man suspected of causing serious bodily harm was arrested.
The injured man entered the building to ask for help. The building is now locked.
The witness, Gareth Milner, stated that he was in front of the Home Office when "several armed police arrived at the scene and entered the building."
& # 39; Deeply concerning & # 39;
"Sometime later, a man with a bloody face and well-dressed clothes was escorted out of the Home Office by paramedics," said Milner.
He said that the man "walked on both feet".
A Home Office spokesman said: "The Metropolitan Police is investigating a knife attack that took place in front of the Home Office this afternoon and the victim is receiving medical attention.
"This is an extremely worrying incident and our thoughts are with him and his family.
"As it is an ongoing investigation, it would be inappropriate to comment further."