Emergency services are dealing with a major incident after a service bus overturned beside the A484 near Kidwelly.
Officers at the scene told the BBC there had been no fatalities.
Dyfed-Powys Police said the collision happened on the road near the Kidwelly roundabout at Parc y Bocs, and declared a major incident.
The single-decker bus, a scheduled First Cymru X11 service, came to rest on its side in a field next to the road at Kingswood, just outside Kidwelly. It is not a school bus or a private coach.
Two Wales Air Ambulances landed at the scene, alongside fire crews, paramedics and police.
Local eyewitnesses have reported at least 26 people were thought to be injured. That figure has not been confirmed by police.
The A484 is closed between the Kidwelly roundabout and Llandyfaelog, and drivers have been asked to find alternative routes.
Local councillor, Lewis Eldred Davies informed residents that those catching the X11 bus service to and from Kidwelly and Carmarthen, “the bus is currently taking the alternative route via Four Roads whilst emergency services are dealing with RTC between Parc y Bocs roundabout and Kingswood”.
A force spokesperson said emergency services were on scene and asked members of the public to stay away from the area until further notice.
Hywel Dda University Health Board said its teams were responding to the major incident, and warned that emergency department waiting times were likely to be longer as staff treated those with the greatest need first.
The board urged anyone needing help to use NHS 111 Wales as a first step if they were unsure where to go.
Mid and West Wales Fire and Rescue Service say that firefighters from Tumble, Carmarthen and Kidwelly were at the scene.
The fire service added that: “All passengers have been safely removed from the bus and are receiving appropriate care. A rest centre has been set up at the John Burns Centre, where welfare arrangements are being made to ensure their comfort and safety.”
Bus operator, First Bus said it was supporting the driver and are working with the emergency services to understand what had caused the accident.
Zoe Hands, Managing Director of First Bus Franchising which covers Wales, said: “Our X11 service was involved in an incident earlier this afternoon (Tuesday 23 June) on the A484 close to the junction with Old Forge Lane, near Kidwelly.
“A team from our depot at Ammanford travelled to scene immediately to support our driver and look after our customers.
“The safety of everyone who travels with us is always our absolute priority and we are working with the police and ambulance service to care for those who need it and understand the circumstances which led to this incident.”
In the Senedd, the Trefnydd and Leader of the House, Heledd Fychan, told members the government was aware of the incident, and said the Deputy Minister for Transport would update the Senedd once more information was available.
The road between the roundabout at Parc y Bocs and Llandyfaelog is expected to remain closed for some time while emergency services respond to the incident and carry out enquiries.
Mid and West Wales Fire and Rescue Service are advising motorists if they are stuck in traffic due to a road closure, to take steps to stay safe in the heat.
It advises to Stay Cool by turning on air conditioning if available, or opening windows to allow airflow when safe. Avoid sitting in direct sunlight – use sunshades or cover windows if possible. If the engine is off, ventilate the car safely to prevent overheating.
It says motorists should Keep Hydrated by drinking water regularly, even if you don’t feel thirsty, avoiding caffeine, or sugary drinks as they can worsen dehydration.
It also urges people to protect the most vulnerable – particularly children, older people, pregnant women, and those with long‑term health conditions – and to never leave anyone (or pets) alone in a vehicle, even for a short time.
