  The dynamics of molecular electron excitation and ionisation is studied in
real-time for ultra-short IR laser pulses of intensity I>10^{13} W/cm^{2}. The
multi-electron molecule is modeled by a system of two active electrons moving
in a field of frozen core. The time dependences of electron probability,
electron energy, and one-electron/two-electron ionisation probability are
calculated for example of the N$_{2}$ molecule and the laser pulse with
\lambda=800 nm, \tau=5 fs. The electron dynamics of the pulse - excited
molecule is considered also after the pulse end. The results show that in the
strong IR pulses of I\ge 10^{16} W/cm^{2} the molecule undergoes a 'cascade'
ionisation, where the one electron is emitted with the same probability as a
pair of electrons.
