Counting in Foyle and East Londonderry constituencies has been suspended due to a security alert.
A suspicious car was abandoned at Templemore Sports Complex in Londonderry.
Army technical officers carried out a controlled explosion on the vehicle shortly after midnight.
Northern Ireland’s assistant chief electoral officer, Graham Shields, said the counts could be suspended until the morning.
Some local residents have been evacuated from their homes and are being put up in a community centre.
Mark Durkan, SDLP candidate for Foyle, said those responsible did not stand for election because "they knew they would get very little support".
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