At this very early stage there is an investigation ongoing, which will look at all aspects of what occurred before the incident and immediately at the time of the incident.
There is a team of very experienced and expert officers in our Serious Collision Investigation Unit, who have surveyed the scene and will systematically interview all witnesses to gather that information.
At this stage it's too early to say exactly what caused the distressing circumstances that led to this collision today.
Again, I'd appeal for any witnesses to contact South Wales Police on 101.
Police have stressed that the incident is not being treated as a deliberate act at this stage.
More top news
Dawn Wilson has terminal cancer - so she's creating a memory book with her daughters of milestones she always hoped she'd share with them.
Jason Piontecki, from Swansea, has been jailed for 15 years after pleading guilty to sexually abusing two children under the age of 13.
The 39-year-old, originally from Gateshead, previously managed Airbus UK Broughton before moving to The New Saints.