A fingertip search was under way today following a mysterious explosion in a remote forest.
A member of the public reported hearing the blast in the Garadhban forest area of Gartocharn, near Loch Lomond, on Wednesday.
Strathclyde Police are investigating damage to trees in the woodland area about 300 to 400 yards from Ross Priory, a 19th century function venue owned by Strathclyde University.
They are being assisted by a team of counter-terrorism officers in an attempt to establish the full circumstances surrounding the incident.
The Northern Diving Group - the Royal Navy's equivalent of the bomb disposal squad - had also been at the scene. Police were unable to confirm the exact nature of the explosion.
However, Chief Superintendent Calum Murray, Divisional Commander, 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 inquiries.
"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."
Police dog vans entered and left the entrance road to Ross Priory which was guarded by a police van and officers. A helicopter was circling over the area earlier today.
Locals have spoken of their concerns.
Stuart King, a group manager with Cawley Hotels and Retail, who was working at The House of Darrach in Gartocharn, on Wednesday, said: "One of my colleagues heard an explosion. She was on her lunchbreak. Then alarm bells started ringing as to what had happened."
Mr King said police called him and asked to meet him at the House of Darrach to get access to the garden store, coffee and gift shop's CCTV.
Mr King said: "It's pretty frightening, very frightening. You wouldn't expect it to happen in a small village like Gartocharn.
"We are just wondering what it's all about.
"The police have been in and re-assured us that everything is fine."
The Scottish Government said police were keeping ministers informed of their progress.
Ross Priory is a secluded building on the banks of Loch Lomond.
It is owned by the university and is used for events including conferences, seminars and weddings.
Speaking near the entrance road to Ross Priory, Chief Superintendent Calum Murray said police expected to be at the scene for "a while yet".
Asked whether the inquiry was related to terrorism, he said: "As I said yesterday, we haven't ruled out any line of inquiry.
"We need to find out what happened. We are using the experts to assist us to do that."
Speaking about the course of the investigation, he said: "We will be guided by those who are making the assessment. I know a lot of time has passed, but these things take time. Today we are in the course of beginning a painstaking fingertip search.
"That is a significant undertaking. That will take a while."
He said: "Broadly you are dealing with an area of woodland in which felling has been taking place and there's wooding operations.
"Clearly we've got a centre of operations that we are focusing on and what we need now, having identified the area we are interested in, is to make sure the entire area is safe.
"We want to reassure the public there is no ongoing or residual threat to them, we have the matters very much under control."
Mr Murray said police were following a "number of lines" of inquiry.
Asked what caused the explosion, he said: "It's far too early for us to determine that.
"The position remains the same in terms of we are taking advice, we are taking whatever material we can identify and that will inform our decisions."
Mr Murray said officers from the Metropolitan Police were helping the investigation.
"In terms of other agencies, as you would expect we've got people with experience with explosives," he said.Reuse content