This article was reproduced with the kind permission
of the British Broadcasting Corporation
10 November 2007, 11:59 GMT
Police said he was struck as he crossed Musselburgh High Street in East Lothian at about 1715 GMT on Friday.
The fire crew based at Musselburgh was on its way to an emergency call in the Wallyford area.
Lothian and Borders Police said initial investigations showed that the fire engine had its sirens on at the time of the accident.
A force spokesman said: "As the fire tender travelled east on the A199 with it's audible warning signs activated a male pedestrian aged 35 years has attempted to cross the carriageway in front of the on-coming appliance.
"He was thereafter hit by the front of the fire tender sustaining life-threatening injuries."
The man was taken to the Edinburgh Royal Infirmary where he remains critically ill.
The road was closed for five hours while an investigation into the accident was carried out.
Police appealed for any witnesses to the accident to contact them.
Lothian and Borders Fire and Rescue Service have not commented.