The M58 has been closed in both directions for several hours after two serious crashes involving multiple vehicles.
The M58 has been closed in both directions between junction 3 (Bickerstaffe, Ormskirk, St Helens, Rainford) and junction 4 (Skelmersdale, Pimbo, Upholland) since a critical incident was declared on the westbound carriageway at around 8.45am.
Four people, including two in their mid-teens, have been taken to hospital.
An NWAS spokesman confirmed that three of those taken to hospital are male, two of whom may be children.
Two of the casualties have been taken to Alder Hey Children's Hospital and two others to Aintree Hospital.
One casualty is in his early 60s and has 'major trauma injuries', according to the spokesperson.
Images from the scene showed a lorry carrying scaffolding material and a number of bent and twisted cars.
The lorry transporting the scaffolding belongs to a Preston firm based at Red Scar Industrial Estate in Longridge Road.
A spokesman for Allied Scaffolding said: "We are fully aware of the situation and it is related to our company.
"We are in full co-operation with the police and authorities and will give them our full support.
"Our main concern at this stage is for those involved in the crash."
Other images showed a white van had left the motorway and crashed into a nearby field.
Helen Green Purnell, 48, a pharmacy assistant from Skelmersdale, saw the aftermath of the crash while out walking dogs.
She said: "All I can tell you is I saw the cars slowing down and as I got there and there was a white van that had fallen down in to the ditch.
"It looked very serious. I've never seen anything like it in my life.
"The air ambulances were flying around. I've never witnessed anything like this before."
According to Highways England, a second collision occurred on the eastbound carriageway.
The full closure has been extended back towards Orrell Interchange in Wigan, where the M58 meets the M6.
Vehicles have been turned around and directed back towards the M6 to pick up a diversion route.
Highways and police are also working towards reopening lanes on the eastbound carriageway, but westbound lanes will remain closed into the afternoon.
It is not known exactly how many vehicles were involved in the collision but Highways and police have confirmed that 'multiple vehicles' were involved.
A fleet of emergency services vehicles descended on the carriageway to deal with the emergency.
Two air ambulances, four land ambulances, police and fire engines are all in attendance following the crashes.
Highways are warning that the M58 is likely to remain closed until late afternoon.
Police are urging people to avoid the area as the closure continues to impact Lancashire's motorway network.
The incident is expected to have an impact on the M6, with traffic being diverted to Orrell Interchange.
More to follow...