South Australia's election is too close to call, with postal and pre-poll votes set to decide the fate of Premier Jay Weatherill's Labor government.

The state's voters swung towards the Liberals, but it is unclear if the change will be big enough to unseat Labor in the key marginals it needs to retain to keep power.

The Liberals needed to win six seats to reclaim government after 12 years of Labor rule, but are so far assured of only three.

Late on Saturday night Mr Weatherill said he was still hopeful of retaining government while Liberal leader Steven Marshall said his side was "still in the hunt".

Look back at how election night unfolded.