The A470 is bi-directionally closed due to a collision between Abercynon roundabout and Merthyr's Pentrebach.
The South Wales police closed two roads to the north of the A470.
There is a car that turned over the road.
Police, fire departments and ambulances are present.
A spokesman for the South Wales Fire Department said, "We received reports of two road traffic accidents.
"Police and emergency medical services attended.
"The driveway to the north was closed by the police.
"Stabilization and door removal are happening now."
Updates to perform: