The family of train driver Brett McCullough, 45, who was killed in the Stonehaven derailment have paid tribute to “the most decent and loving human being we have ever known”.

Train conducter Donald Dinnie also died in the crash as well as a passenger.

In a statement, McCullough's family said: “Words cannot describe the utterly devastating effect of Brett’s death on his family and friends.

"We have lost a wonderful husband, father and son in the most awful of circumstances.

READ MORE: Investigators seek answers in derailment that killed three

"Brett was the most decent and loving human being we have ever known and his passing leaves a huge void in all our lives.

“We would like to thank the emergency services for their heroic efforts in helping everyone affected by this tragedy and for all the messages of support and condolence we have received." 

The "extremely private" family have asked to "grieve without intrusion". 

The RMT union has paid tribute to its member Donald Dinnie, who died in the Stonehaven derailment along with the driver and a passenger.

HeraldScotland: Conductor Donald Dinnie died in yesterday's train derailment.Conductor Donald Dinnie died in yesterday's train derailment.

Senior assistant general secretary Mick Lynch said: “On behalf of the union I want to send condolences, support and solidarity to Donald Dinnie’s family‎, friends and colleagues.

“It is absolutely clear that he was much loved and highly respected by all who knew him and his death is a tragedy that has shocked our entire industry. We share the grief of those who were close to Donald.

READ MORE: Three killed in derailment only weeks after risk warning

“Donald’s branch, Aberdeen 1, have told me that ‎he was an amazing person. He lit up every room he walked into with his cheery banter and stories. Many knew Donald for most of his railway career as a driver and a guard. He was very much a family man and a valued, active and proud member of the RMT.‎ His loss has cast a long shadow over his branch, his Region and the whole national union.

“Our thoughts at this time are also with the driver,‎ Brett McCullough, a member of our sister union ASLEF, and the passenger who also lost their lives in yesterday’s incident.

“RMT will continue to provide whatever support we can to Donald’s family and colleagues at this terrible time. We are united in both our grief and our determination to ensure that safety on our railways remains the absolute priority.”

Four of the patients injured in Wednesday’s train crash near Stonehaven have been discharged from hospital.

A spokeswoman for NHS Grampian said: “Following yesterday’s major incident, four patients have been discharged from Aberdeen Royal Infirmary.

“Two remain in hospital, both are in stable condition.”