The elections were brought about by the resignation of Deputy First Minister and IRA commander, Martin McGuinness and the refusal of Sinn Féin to put forward a replacement candidate. The convicted terrorist didn't stand due to a serious illness.
The Single Transferable Vote system is notoriously difficult to predict but early indications are that the DUP will finish with most seats but Sinn Féin will be a close second whilst UKIP could end up with one seat.