A man at the centre of a stand-off with armed police in north-west London is feared to have stockpiled petrol.
The Met Police say they are “treating seriously” reports that the man has “quantities of petrol and combustible material” at his home in Northolt.
Armed officers have been outside since the early hours of Friday. The Met, who are concerned about his mental health, say he has “not engaged at all”.
About 80 residents have been forced out of their homes.
A 200m (650ft) cordon has been in place around the property on Wood End Lane since Friday.
No attempts have been made to enter the house over fears such an action “may make his behaviour unpredictable”.
The Met said it could take some time to end the stand-off safely.
Ch Supt Paul Martin said: “Our aim is to bring this to a safe conclusion for everyone. I know that our operation has been ongoing for some time now and that it is causing disruption and inconvenience to local residents and the community of Northolt.
“I would like to thank them for their continued patience and co-operation.”
He added: “The operation will continue for as long as is necessary and I would like to stress that we are doing all we can – using all our tactics – to end this incident safely.”
BBC reporter Ayshea Buksh said neighbours had told her the man had “aggressive, dangerous dogs”, which was one of the reasons why police were being particularly cautious.
A woman claiming to be the cousin of the man told the BBC he had recently had a “breakdown”.
The man is believed to be in his 40s and, according to several local residents, has regularly been seen walking four Rottweiler dogs.
Ealing Council said the vast majority of evacuated residents had made their own arrangements but the elderly, vulnerable or those with young children had, where necessary, been placed in bed and breakfast accommodation.
The authority’s leader Julian Bell said: “They’re a little bit frustrated by the disruption; they’ve got lives to get on with and jobs to go to and they want to be able to return to their homes.
“But equally they recognise that everybody’s got to be kept safe. We want a safe outcome and nobody to be hurt. So I think they’re bearing it with patience and forbearance.”