Two firefighters remain in hospital after the vehicle they were in came off the road.
The Haddington crew had been called out to help after an earlier accident when the incident occurred.
Firefighters from North Berwick and Musselburgh used hydraulic rescue equipment to free their colleagues, who were trapped in their vehicle.
All six crew members were taken to Edinburgh Royal Infirmary for treatment after the accident, which took place at 9.50pm on Sunday on the A198 between Ballencrieff and Longniddry in East Lothian.
While four of the firefighters were discharged, the Scottish Fire and Rescue Service confirmed two remain in hospital
John Dickie, local senior officer for the area, said: "Our thoughts and best wishes are with our personnel who were injured in last night's road traffic collision.
"All six were taken to Edinburgh Royal Infirmary following the incident, four were subsequently released following treatment and two remain in hospital. We wish them all a speedy recovery."
He added: "Welfare support has been put in place for all crew members and their families.
"Alternative fire cover arrangements have also been instigated for Haddington whilst affected personnel are off-duty."
The fire engine was the only vehicle involved in the crash, the cause of which is not yet known.
Police Scotland are investigating in a bid to determine what happened.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article