Metropolitan Police officers are negotiating with a man thought to be in possession of a gun after he is alleged to have broken into a home in Tilson Garden, Streatham, in south London.
Officers went to the home on the morning of 21 August to reports a man broke in and was armed with a firearm. About 20 police vehicles are at the scene and there are reports at least one resident has been evacuated.
A Met spokesman said: "We were called this morning to reports a man had broken into a property at Tilson Gardens. While there, officers were threatened by the man, who is thought to be in possession of a firearm. Officers remain at the scene and the incident is ongoing."