As they reported loss of oil pressure, that would make sense. A hot manifold makes a perfect igniter. Takes high heat to get it going but once it is lit, diesel fuel contains parafin in suspension, which keeps the burn going. That is the nature of diesel, does not explode like gasoline, but has a long burn after the heat of compression sets it off. Dense black smoke would indicate the engine oil burning as well which would help fuel the diesel. I was a diesel bus mechanic for many years, saw it happen several times.