The Home Office in Westminster was on lockdown on Thursday afternoon after a man in his 60s was stabbed outside the building.
Specialist firearms officers were called to Marsham Street at around 1pm amid reports of a man with a knife. Images shared online appeared to show a heavily bloodied man wearing a suit jacket being helped away from the scene by a paramedic and an armed officer.
The victim’s injuries have been described as neither life-threatening nor life-changing by the Met Police.
A 29-year-old man was arrested near the scene at Smith Square on suspicion of grievous bodily harm and possession of CS spray, and taken to a central London police station.
On Thursday evening, it was confirmed that the man injured works for the Ministry of Housing, Communities and Local Government (MHCLG).
Communities Secretary Robert Jenrick said: “I am deeply shocked by this horrific attack on a colleague today.
“My thoughts, and those of all my staff, are with him and his family. We are ready to provide as much support as we can and we all wish him a speedy recovery.
“We will be reviewing security across the MHCLG estate. All our staff must feel safe as they go about their important work.
“I would like to give my heartfelt thanks to the police, ambulance service and our staff for their swift response today.”
A police spokeswoman previously said it was too early to say whether the incident was linked to the Home Office, but there was no suggestion it was terrorism-related.
Eyewitness Guy Ellis, 54, described seeing a man remove a “long” knife from his bag before the incident.
“I was sat outside the Home Office waiting for a friend to meet for lunch and on the other side of the entrance I just saw a bloke take a knife out of his bag, and just wander up the path, stop in front of two girls who were just sat there having a chat, and then he wandered back and turned round and crossed the road very calmly and merged into the crowd.”
He said the knife was “long and thin” and “pointy”.
Another eyewitness Gareth Milner said he was eating his lunch on the wall outside the Home Office when “a number of armed police officers arrived on scene and entered the building”.
“Some time later a gentleman with quite a bloodied face and with dressing pressed into his face was escorted out of the Home Office by paramedics,” said Milner, who works nearby for the Centre for Policy Studies think-tank.
“He was quiet and walking on his own feet, not being physically supported,” he added.
An office worker opposite the Home Office, who asked to remain anonymous, described seeing a man – thought to be the perpetrator – walk calmly down the road after the incident.
She told PA: “He was standing over there outside the Home Office and then he was putting something away in his bag, but I didn’t see a knife or anything.
“He was putting something away and then he just calmly just walked off down the road as if nothing had happened.
“Then people were being asked to go into the Home Office, they were being ushered in.”
A police cordon remains in place around the buildings.
A spokeswoman for the Home Office said: “The Metropolitan Police is investigating a knife attack which took place outside the Home Office this afternoon.
“The victim is receiving medical care. This is a deeply concerning incident and our thoughts are with him and his family.
“As this is an ongoing investigation, it would be inappropriate to comment further.”