Vote counting was underway in Zambia on Friday after a hard-fought general election that saw social media throttled in the capital and President Edgar Lungu send more troops to three provinces to quell violence.
Violence was reported in the North-Western province, a Hichilema stronghold, where two people including a ruling Patriotic Front (PF) party chairman were killed, the president announced late Thursday, blaming his rival's United Party for National Development (UPND) party.
Zambia's electoral commission has launched an investigation into the chairman's murder, which the UPND distanced itself from, calling it a "distraction" tactic.
The PF also alleges some of its agents were beaten and chased from polling stations in the Southern province.
Lungu, who had deployed the military to police the vote following pre-election clashes, reinforced troops in three provinces.
There are fears the president could be "exaggerating the extent of violence and instability in opposition regions to justify" invalidating their results, Nic Cheeseman, British political scientist and author of "How to Rig an Election", tweeted on Thursday.
Social media access has meanwhile been throttled since Hichilema cast his vote in the capital Lusaka, raising eyebrows among the electorate.
Bleary-eyed polling agents were still counting ballot papers as the sun rose over Vera Chiluba primary school in central Lusaka on Friday, sifting through the final batches in a classroom.
Voting continued hours after polls closed at 6 pm (1600 GMT), with many of the more than seven million registered voters queueing through large chunks of the day to cast their ballot.
Final official results of the presidential, parliamentary and local government elections are expected by Sunday, although partial and unofficial tallies were already circulating.
Poll watchers have warned of possible unrest when the results are out.
The outcome is expected to swing on results in Lusaka, a bustling city of more than 3.3 million, and in the central Copperbelt province -- the key to the economy in Africa's second-largest copper producer.
Hichilema, who is running against Lungu for the third time, only lost by around 100,000 votes in 2016 and an even narrower margin in a by-election the previous year.