A woman was taken to hospital after a five-vehicle crash near Chester.
The accident took place on the A483 at 6am at junction seven between Rossett and the Posthouse Roundabout.
Police were forced to close the northbound carriageway for more than 90 minutes as debris was left scattered across the road.
One of the cars smashed into the central reservation and was left blocking lane two – causing motorists to take evasive action.
A woman was taken to the Wrexham Maelor Hospital via emergency ambulance, but her condition is unknown.
A Welsh Ambulance Service spokesman said: “We were called at shortly before 6.10am to reports of a multi-vehicle road traffic collision on the A483 northbound near Rossett. Two emergency ambulances attended the scene and an adult female was taken to Wrexham Maelor Hospital."
The road closure caused huge delays on the A483 during rush hour.
While diversionary routes including the A541 in Gwersyllt, the A550 in Cefn-Y-Bedd and the B5445 through Pulford were also jammed – with motorists reporting delays of up to two and a half hours.
One motorist who witnessed the aftermath of the collision described the scene.
She said: “I drove by just after it happened at about 6.10am and it was carnage.
“There were four cars lined up on the side of the road in the first lane and another car had hit the central reservation and was blocking the second lane but it’s lights had stopped working and the police hadn’t arrived yet so I didn’t even realise it was there until the last minute and had to quickly swerve to avoid hitting it.
“There was lots of debris on the road – it was an absolute mess and just chaos.”
North Wales Police re-opened the road at around 7.30am but delays lasted until around 10am.