electrodynamics, cartoon style.
Ok, technically speaking a magnetic field can't do any work on an electron it can just sorta alter it's course.
This is also true for a magnetic (B) field that is changing in time but a time varying magnetic field is directly related to a time varying electric field which can do work on an electron and accelerate it the hell out of there.
Here is the URL of a cartoon showing sorta how it works. Reconnection is the point at which the red and blue field lines make an X.
http://www-istp.gsfc.nasa.gov/istp/news/0005/reconnect_flux_steady