A visitor has described how paramedics desperately tried to bring the boy back to life.
Cllr Carl Marshall said: "I was visiting the museum with the family. We were in the events field. We noticed an incident."
"There was what appeared to be a child. There were Beamish vehicles on scene. The paramedic arrived and started to work on the casualty. Within a couple of minutes things got more frantic. A defibrillator came out."
"The after a couple more minutes they walked away and a blanket came out."
"It's a tragic event and it has rocked this community."
Police confirm the engine involved in an incident in which a boy died at Beamish was being driven by his father.
A seven-year-old boy was killed in the incident with a steam traction engine and trailer at the Beamish Museum.