Something's happening down at the old railway

I went for a run on my bike on the old railway and as I was approaching Rosewell there was a policeman on a quad bike talking on his radio. I thought nothing of it, but on the way back as I was nearing the viaduct before the site of the old paper mill there was a woman police officer standing next to two quad bikes. Then I came across another 4 policemen who had left there cars at the foot of the hill and the footpath had been taped off . As I reached the foot of Grahams road another two police cars went down and then after crossing the road another two cars came down.