Most spoke failures are fatigue failures due to normal stress cycles (riding over bumps etc.). One day they eventually just go 'ping'.
How long it takes depends on things like the thickness of the spokes, their quality, whether they're butted, overall spoke tension, evenness of spoke tension, etc. etc.
However a sharp sideways impact can break a spoke fairly easily so it could have been either.
Most spoke failures are fatigue failures due to normal stress cycles (riding over bumps etc.). One day they eventually just go 'ping'.
How long it takes depends on things like the thickness of the spokes, their quality, whether they're butted, overall spoke tension, evenness of spoke tension, etc. etc.
However a sharp sideways impact can break a spoke fairly easily so it could have been either.