Unverified posts on social media later speculated that the collision had been brought on by a police chase.
Police urged individuals “to not speculate” on-line, and stated the crash had already occurred earlier than officers arrived.
In an preliminary assertion on Twitter, South Wales Police Cardiff stated: “Emergency companies are on the scene of a severe street visitors collision on Snowden Highway, Ely.
“The street is closed between Wilson Highway and Jackson Highway. Please keep away from the realm and take another route.”
In a later replace, the power stated there have been “now a lot of officers working to handle the collision”, but in addition to “de-escalate ongoing dysfunction on the scene”.
“We urge anybody concerned to depart the scene instantly and ask native residents to remain away whereas the matter is dropped at a secure conclusion,” police stated.
“Emergency companies stay on the scene. It will be important that individuals keep away from the realm so we will successfully cope with this incident.
“Please keep away from hypothesis – we are going to convey you the most recent particulars as quickly as we will – all of our updates have to be factual.”