Tezpur reported 56 per cent polling, Jorhat 60, Lakhimpur 52, Dibrugarh 52.5 and Koliabor 60 per cent, election office sources said.
Prominent contestants in the fray are union ministers and contestants Paban Singh Ghatowar (Dibrugarh) and Ranee Narah (Lakhimpur), former union minister and sitting Congress MP Bijoy Krishna Handique (Jorhat).
Chief Minister Tarun Gogoi's son Gaurav (Koliabor), besides Congress rebel and independent candidate Moni Kumar Subba and BJP state unit president Sabananda Sonowal (Lakhimpur) are also locked in the electoral battle.
Police said four persons, including a woman, suffered injuries when they clashed with CRPF personnel demanding they be allowed to cast their vote early at a voting centre in Sarupathar Silonijan area of Kaliabor constituency.
A Congress ward member B L Sahu was injured when a BJP worker of Bojali Tea Estate at Duliajan in Dibrugarh constituency attacked him. Sahu had allegedly tried to bribe him to vote in favour of Ghatowar, the Congress nominee.
Rupahihat AIUDF MLA Mujibur Rahman alleged that party supporters were threatened by local Congress leader Muzammil Hussain at Hatipukhuri polling station in Kaliabor.
At least 40 EVMs malfunctioned in Dibrugarh, Kaliabor, Tezpur and Lakhimpur constituencies, the sources said adding 29 of them were replaced and snags in the others rectified for voting to continue uninterrupted.
Chief Minister Tarun Gogoi, who was talking to reporters after casting his vote at Jorhat, exuded confidence and said Congress would sweep the polls in the state and win more than 10 of the 14 Lok Sabha seats in the state.
"There is no Modi magic, but Tarun Gogoi magic in Assam. Earlier, I had said we will win ten seats but now I am sure the Congress will get more than that," he asserted.
Besides Congress and BJP, Trinamool Congress, AIUDF, AGP, AAP, SUCI, CPI(M), AIFB and SP are in the fray in the five seats.