Justine Sims, headteacher of Pontville School in Ormskirk, paid tribute to 14-year-old pupil Joe Cairns and staff member Anne Kerr, 50.
They died in a multi-vehicle crash close to junction three of the M58 westbound at Bickerstaffe on Tuesday.
In a statement issued on Thursday, she said: "Our hearts are filled with sadness as we grieve the loss of these two much loved individuals who are both valued members of our school community.
"It is really hard to describe Joe in just a few sentences. A lovely young boy with the most amazing sense of humour. Bright, articulate and observant, a ray of sunshine and laughter for all at Pontville School. Joe is in our hearts and minds forever.
"Anne, a pupil transport assistant, was a caring member of staff who went out of her way to support the young people at Pontville.
"We have been inundated with condolence wishes for both Joe and Anne from our families and pupils, including those involved in the incident. Our thoughts and sympathies are with both families at this difficult time. Our thoughts are also with our staff member and three pupils who were injured in the accident and are currently in hospital.
"This is an enormously distressing time for everyone associated with the school. Our priority is to provide as much support as we can for pupils, parents, colleagues and families. We have brought additional staff in from other schools in our group to help, including mental health practitioners and psychologists, and this assistance will continue for as long as it is needed."
Joe, from Radcliffe in Bury, and Mrs Kerr, from Southport, were travelling in a minibus carrying pupils and staff from the special educational needs school.
The collision, which also involved a HGV and a number of other vehicles, happened at about 9am.
The driver of the HGV, a 31-year-old-man from Chorley, was arrested on suspicion of causing death by dangerous driving. He has since been released under investigation pending further inquiries.
A number of other people were seriously injured in the incident and continue to be treated in hospital, said Lancashire Police.
A second collision took place at around 10.10am in the queuing traffic, involving an HGV, a van and two cars.
A woman and two men suffered serious injuries in that crash.
Police are continuing to appeal for information about both collisions and would like to receive relevant dashcam footage.