Police have closed off a stretch of the M4 in south Wales following a "serious" crash.
Officers arrived at the scene between junction 25 and 26 eastbound following a smash involving a lorry, bus and a number of cars at around 9.30am.
A force spokeswoman said: "At the moment we have two reported casualties the driver of the bus and a passenger who was on the bus.
"The motorway has been closed in both directions between junction 24 and 28 so that the Air Ambulance can land and diversions are in place."
Gwent Police said it is at the scene, which is near Newport, together with the fire service and ambulance service.
Early indications are that the coach is carrying students from abroad - 57 passengers in total.
Gwent Police Chief Inspector Paul Evans said: "We appreciate the closure is causing problems for motorists, however the decision to do so is never taken lightly and we fully recognise the impact this has on motorists as well as the communities affected by diversions.
"We need to ensure we investigate every such collision thoroughly gathering all evidence possible and also ensuring the safety of everyone involved as well as other motorists who will be using this road once it's reopened.
"We are grateful for the understanding and patience shown by drivers and their passengers today.
"Motorists are advised of possible delays and are advised to avoid the area if possible."