An air ambulance was called to the Kirkham junction of the M55 following a five vehicle crash, say police.
Police, fire and ambulance services also rushed to the scene of the collision between the vehicles which included a HGV and a white Ford Fiesta on the westbound carriageway at around 8.45am this morning.
Ambulance services reported that they treated three patients at the scene one of which was unconscious when paramedics arrived.
The air ambulance landed but it was decided to take the patients to hospital by road ambulance, a spokesman for NW Air Ambulance said.
The westbound carriageway of the motorway remains closed and a rolling road block has been put in place on the eastbound carriageway between junctions 1 and 3 while trapped traffic is turned back to Preston.
Sgt Steve Wignall, of the Roads Policing Unit, said: “This was a serious collision which occurred in busy morning traffic and we are very much in the early stages of piecing together what happened and what the level of injuries are.
“We would like to thank motorists for their patience while we continue our investigation. We will reopen the motorway fully as soon as we possibly can.”
Firefighters from Fulwood and Preston worked to free a person who was trapped in the wreckage.
A spokesman for Lancashire Fire and Rescue sad: "We attended the scene of an accident on the M55. Injuries were reported although we currently do not have any details of what these injuries are.
"A person was trapped but they have now been freed with the help of paramedics.
"The collision involved two lorries, two cars and van.
"Firefighters from Fulwood administered first aid to two casualties then on instruction from the paramedics at the scene monitoring a third casualty's medical condition conveyed the casualty out of one of the cars."
Highways England said in a statement: "Road users are advised to follow the Solid Circle symbol led diversion and to allow extra time to complete their journey plans or should consider an alternative route. Normal road conditions are expected at around 6.30pm."
Motorists stuck in the jam close to the accident were left confused after some cars turned around and went back along the hard shoulder.
One driver who had an appointment at Whitehills said: "I am glad that I wasn't a few minutes earlier because I could have been in that crash. But it would be good for the police to have at least opened one lane to let the traffic go on to Blackpool. There didn't appear to be much debris in the outside lane."
Anther man heading to a building site in Blackpool said: "I guess it must have been very serious and they are collecting evidence at the scene.
"People turning round were being a bit stupid before the police ordered them to as they could have blocked emergency services on the hard shoulder."
One lane of the westbound carriageway was re-opened at around 2.30pm to allow trapped vehicles past the scene.
Screens have now been errected around the accident site.
This is a developing story.