The incident, which is not considered terrorist, happened around 8.50am on Monday morning at the Horse Guards Parade, not far from Downing Street 10 and Whitehall. The 29-year-old suspected teaser was detained by police, the Metropolitan Police said. There were no reports of injuries. Image: A police medical examiner enters the Horse Guard building as a police officer guards The man has been arrested on suspicion of attempted murder and possession of an assault rifle and remains in custody at a central London police station. A spokesman for the Metropolitan Police said: “The investigation is ongoing. “The officers of the meeting will continue to come in close contact with the Police of the Ministry of Defense as it progresses” Anyone who has seen the incident or has any other information is kindly requested to contact the police at 101.