Unfortunately it is understood that the driver of the SWR train has received life-changing injuries - BBC News. Also, note in the pictures, that the points remain set for the Romsey line.
The units in the pictures appear to be 3 coach 159102 (not a 3 unit, 9 coach, set as recorded on Sunday) and 2 coach 158763. The lead coaches of each are in the tunnel.158762 separated forward of 158763 - images.
Jack Boskett's photos.
BTP statement. "at this early stage there has been nothing to suggest the train struck an object or that there was any significant delay between the trains colliding and then one derailing".
Salisbury Journal.
Trains not expected to be removed until 8th November.
Apart from updates on the removal of the damaged trains and recovery of the infrastructure, it is probably best to await the interim report from RAIB.