Emergency services have taken two people to hospital in a critical condition after a crash near Ormskirk.
The crash happened in Moss Lane, Burscough at around 4am and involved a number of vehicles.
It is believed that one of the vehicles also collided with a telegraph pole.
North West Ambulance Service said two casualties have been taken to hospital in a critical condition.
An NWAS spokesman said: "We were called at 4.01am to a road traffic accident in Moss Lane, Burscough.
"We sent two ambulances, a rapid response unit, an advanced paramedic and a Hazardous Area Response Team to the scene.
"Two people were taken to hospital."
NWAS said it was unable to provide details on the casualties' current condition.
The Hazardous Area Response Team (HART) is made up of specially trained paramedics who attend incidents that are declared a major incident.
Moss Lane remains closed in both directions, between Sluice Lane in Rufford and Red Cat Lane in Burscough, whilst police continue to investigate.
The A59 junction with New Road, near the Hesketh Arms pub, has also been closed.
Fire crews were also called to the scene to free trapped casualties from the vehicles.
An LFRS spokesman said: "We attended an road traffic accident at 4.05am in Moss lane, Burscough.
"We sent two fire engines from Ormskirk.
"We helped free a number of casualties who had been trapped inside the vehicles.
"We were on the scene for around two hours and were stood down at around 6.20am."
Police are urging people to avoid the area, with the A59 expected to remain closed for some time.
A police spokesman said: "We are asking motorists to continue to avoid the A59 between Burscough and Rufford as the road is still closed due to a serious collision.
"We were called at around 4.10am this morning to a report that a number of vehicles had collided.
"A number of people have been injured as a result and the road remains closed between Red Cat Lane in Burscough and New Road in Rufford whilst we investigate and repairs are carried out to a telegraph pole.
"Red Cat Lane in Burscough and the surrounding roads are congested and traffic in Rufford is being diverted towards Mawdesley which is also making the B5246 very busy.
"We'd urge people to avoid the area if possible for the remainder of the morning.
"We will let everyone know as soon as the road has re-opened."