LONDON — Britain's elite firearms police unit rushed to the U.K. interior ministry Thursday after a man was stabbed outside the government building, police said.

Officers arrived within six minutes of reports of a man with a knife outside the Home Office, the department that handles domestic policy such as crime, immigration and counterterrorism.

Police arrived to find a man in his 60s had been stabbed, according to a statement from London's Metropolitan Police. They initially said the man had life-threatening injuries but later said that his life was not in danger.

Another man, 29, was arrested nearby on suspicion of grievous bodily harm and is in custody at a police station, police said. Neither person has been identified.

Sending armed police to the incident indicates the severity with which authorities first responded, as vast majority of British police do not carry guns.

"Inquiries are ongoing into the exact circumstances of the incident," the statement said. "We are keeping an open mind about any possible motive at this early stage."

The stabbing happened on Marsham Street in or around the Home Office. A Reuters photographer saw a man with facial injuries and blood on his front being led from the building.

According to Reuters, a police spokeswoman 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.

Andrea, who works at a cafe opposite the building, said she only knew something was wrong when she saw a man covered in blood walk outside.

"He was older than 50 and had blood on his tummy and his face," said Andrea, 29, who declined to give her last name. "I didn't know what was happening. I just saw him walk out with a paramedic."

She said police officers came to the cafe to ask staff to keep an eye out for anything suspicious, adding that she had never seen anything like this before.

An hour after the incident a police cordon was still up outside the government building, but life appeared to be returning to normal on Marsham Street with office workers taking a break to eat their lunch or have a cigarette.

Cafes on the street were open and most of the road was accessible to pedestrians.