An incident happened in Stockton High Street on Saturday night which left a man in a hospital major trauma centre.
His condition on Sunday is still unknown.
Cleveland Police has yet to comment on the incident which saw part of the road, close to the Clock Tower pub, cordoned off.
However, one witness who was at a bus stop over the road says the injured man was attacked, being punched to the face, falling and hitting his head.
This detail has yet to be confirmed by authorities.
Footage from the scene, taken by photographer Terry Blackburn, shows the police operation that ensued.
Here’s what we know so far on the incident.
999 calls were made to emergency services on Saturday night around 7.15pm reporting that a man had been injured.
Reports on social media suggest a man was found lying on the ground, and a witness, Adele Hardwick, 25, says he was laid out for quite some time after being punched by another man.
Other passersby reported seeing a small amount of blood on the floor close to where he was laying.
He is believed to be aged in his late 20s or early 30s. This has also yet to be confirmed officially.
Which emergency services attended?
Paramedics from the North-east Ambulance Service went to the scene in two ambulances.
Officers from Cleveland Police were also there, followed closely by scenes of crime officers.
The area was cordoned off for investigations to take place.
What did scenes of crime officers do?
The forensics officers covered themselves with protective white suits, hair nets, shoe covers and face masks in a bid to start gathering potential evidence.
Due to the time of the incident and the darkness, floodlights were erected around the cordon to make it easier for them to see.
Yellow evidence cones were placed on the ground marking areas of interest.
The cordon – near McShane’s and The Clock Tower – remained in place for several hours but had been removed by Sunday morning.
Where was the man taken?
The injured man was taken to the Major Trauma Centre at James Cook Hospital, in Middlesbrough.
On the South Tees Hospitals NHS Foundation Trust website it states that the centre is “able to deal with injuries to all parts of the body and here at James Cook we receive both adults and children with significant injuries.
“A wide range of specialised trauma doctors and nurses are available 24 hours a day and we are able to deal with very badly hurt patients that may arrive either by ambulance or helicopter.”
The man’s condition and injuries are not known.
What have emergency services said?
A spokeswoman for the North East Ambulance Service said: “We received reports of a person injured in High Street, Stockton, at 7.15pm.
“We dispatched two double crewed ambulances and transported one patient to the James Cook major trauma centre.
“The patient was a man, we can confirm.”
Teesside Live has contacted Cleveland Police for any updates or information.
Were there any witnesses?
One woman, Adele Hardwick, 25, from Primrose Hill, in Stockton, saw the incident unfold.
She says the injured man was attacked and punched once by another man.
The mum-of-one, who works as a carer said: “The man fell and hit his head off the floor. The noise was awful.”
Bus passengers were left upset at the incident with one teenager crying.