Fire Walker Instant Death

Is there instant death with a fire walker? That just happened to me when it got me into the struggle. It was one of the big walkers, so I'm not sure if this has any impact on it. Is there any case where two of my walkers are full health but the third is low health, hit by a fire tank, and suffers instant death and mission loss?
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What are Burning Walkers?
Since walkers are not killed by fire, you may run into Burning Walkers that are marked by a flame icon.
Every time your survivors are in melee contact with burning walkers, they take burn damage. You can avoid burn damage by using ranged classes (hunter, shooter, assault) to attack.
Notice that with burning walkers struggles only last 1 turn, so save them quickly!
Feeling Lost, Click Here!
I learned my lesson from that one. So, if you are already low on health, be prepared to die if you get hit by a burning walker of any type.
On a side note, I let several walkers burn a bit and some died before I could even attack them. But I don't know if that is still the case.