dash board lights stay on when ignition is off?

dash board lights stay on when ignition is off on peugeot 406 hdi 1999.when I was driving along the airbag light started flashing ,then ny speedo and rev counter stopped working then when I indicated the indicator light on the dash did not come on then the stop light came on and when I pulled over and pulled the key out all the lights on the dash stayed on!!.has anyone experinced this as really need HELP with this one.