Specialist police officers are carrying out a "fingertip search" at the scene of an explosion in a Scottish woodland.
The site in Ross Priory Wood, near Gartocharn, at the south of Loch Lomond, has been closed off since the blast was heard at midday on Wednesday.
It has been reported that devices have been found in the area.
Police have refused to confirm the nature of the incident but anti-terrorism officers and bomb disposal units have been part of the operation.
The latest briefing from Strathclyde Police, which is leading the investigation, said a number of specialist officers were currently searching the scene.
This team includes officers from the Metropolitan Police and scientific and Explosive Ordnance Disposal (EOD) trained personnel.
The force said the level of detailed search required was likely to "take some considerable time".
Ch Supt Calum Murray, divisional commander in Argyll, Bute and West Dunbartonshire, said: "The priority yesterday was to make sure that there was no risk to the public or officers in order that initial investigations could take place.
"We can assure everyone that this area is secure and there is no risk to anyone living, working in or visiting the area.
"Today we began the painstaking task of searching the area for any evidence. We would like to thank the public for their co-operation and assistance so far in our initial enquiries.
"We would also ask for their continued patience as I am sure they understand that we must follow strict procedures in order that we carry out a thorough investigation."
The investigation is focussing on damage to trees in the woodland area about 300 to 400 yards from Ross Priory, a secluded 19th Century building to the south east of the loch.
Ch Supt Murray previously said the site was "not an expansive area".
Van loads of police officers have been coming and going from the scene and several boxes marked evidence were removed on Friday morning.
A Metropolitan Police helicopter was also seen flying over the area.
Officers are also collecting CCTV footage from local businesses within the general area of the explosion.
Hotel manager Stuart King told the BBC: "I got a phone call from CID asking if I could meet them here as a matter of urgency and that they wanted to access our CCTV system."
Mr King said the officers gave him no details about why they were scrutinising the footage.
He added: "We heard rumours that there had been an explosion and then saw it on the news website."
A Scottish government spokeswoman said: "Strathclyde Police are currently investigating this incident and are keeping ministers informed of their progress - they have reassured us that there is no threat to public safety."