A man carrying an axe has been arrested near Buckingham Palace, police have said.
Metropolitan police officers were on patrol when they spotted the man, believed to be in his forties, walking on the Mall in central London holding the weapon at around 6.30pm on Tuesday.
Armed officers were on duty nearby and the suspect was detained and arrested on suspicion of carrying an offensive weapon.
The Met said there are no reports of any injuries and the man was taken to Charing Cross police station for questioning. The force said enquiries are continuing.
Photos from witnesses on Twitter appeared to show several officers surrounding the suspect near the Institute of Contemporary Arts building.
Anyone with any information is urged to contact police on 101 or Tweet @MetCC quoting CAD 6041/13APR.