Congress chief D D Lapang, former chief minister S C Marak and United Democratic Party president Donkupar Roy have won from Nongpoh, Resubelpara and Shella constituencies respectively.
The Congress is poised to increase its tally from the 2008 Assembly election when it had bagged 25 seats.
Incumbent Chief Minister Mukul Sangma has won from Ampati seat defeating his NPP rival Clement G Momin by over 9,000 votes.
Mukul's wife D D Shira and brother Zenith Sangma are also comfortably leading in their respective constituencies in the Garo Hills.
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The UDP is set to retain at least seven seats.
Among the 122 Independent candidates, six have won while another seven are leading in their respective constituencies.
While only 27 seats have been officially declared so far, Chief Election Officer P Naik told PTI that counting is over at all polling stations and declaration of results is awaited for final confirmation.
Prominent winners are cabinet ministers Ampareen Lyngdoh, H D R Lyngdoh, Prestone Tynsong, R C Laloo, A L Hek.
HSPDP chief Hopingstone Lyngdoh retained his seat for the eighth consecutive term since 1972.
His party colleague Ardent Basaiawmoit retained his seat from 22-Nongkrem constituency.
Speaker in the outgoing Assembly Charles Pyngrope is trailing by a margin of 979 votes in Nongthymmai constituency.