British police arrested a man armed with a knife who confronted two Ministry of Defence police officers near Prime Minister Boris Johnson's official residence in central London on Monday.
Police cordoned off Whitehall, which is home to several government departments including the Foreign Office and Ministry of Defence and leads to Johnson's Downing Street office and residence, for several hours but it was later reopened.
An investigation was launched following the incident at Horse Guards Parade, a ceremonial parade ground that overlooks St James's Park, police said.
"At around 8:50 a.m, a 29-year-old man, who was armed with a knife, confronted two Ministry of Defence Police officers. A taser was deployed and the man was restrained by officers. There were no reports of any injuries," London's Metropolitan Police said in a statement.
"He was arrested on suspicion of attempted murder and possession of an offensive weapon and remains in custody at a central London police station. The incident is not being treated as terror-related."