Shreen Saroor, an activist working with displaced Muslims, said the attack made them more determined to vote and they were using public transport and private vehicles to get to the polling stations in Mannar.
According to the latest update of the CMEV, Sri Lanka Podujana Peramuna (SLPP) party of opposition candidate Gotabaya Rajapaksa reportedly committed the majority of election violations, with 130 incidents, while ruling party candidate Sajith Premadasa's New Democratic Front had committed 45 election-related violations.
Police reported to the independent election commission that the army was illegally manning roadblocks that could discourage residents from freely travelling to polling booths.
One of the two frontrunners is grey-haired retired army lieutenant colonel Gotabaya Rajapaksa, 70, younger brother to the charismatic but controversial Mahinda Rajapaksa, president from 2005-15.
President Maithripala Sirisena, who was elected in 2015, is not seeking reelection.
Police also arrested 10 men there suspected of "trying to create trouble", a police official said.
Votes will be counted soon after polling stations close that evening but the results are not expected before Sunday.
Almost 16 million of the 22 million people were eligible to vote and choose a new president from a record 35 candidates.
Campaigning was dominated by worries over national security, which was pushed to the forefront after deadly Islamic State-inspired suicide bomb attacks on Easter Sunday that killed 269 people.
Mr Premadasa, the son of a former president who was assassinated by a Tamil Tiger suicide bombing, has gained support in recent weeks by promising to expand welfare programs and bringing disgruntled party stalwarts into the fold.
The Rajapaksas are adored by Sri Lanka's Sinhalese majority for defeating the Tigers and ending Sri Lanka's 37-year civil war in 2009 in which around 100,000 people lost their lives on the Indian Ocean island nation of 21.6 million.
At a polling station in Colombo, M. Gunasekera, a 41-year-old homemaker, said the most important problem was widespread corruption and the lack of accountability of politicians.
"The gunmen opened fire and also pelted stones", a police official in Tantirimale, 240 kilometres (150 miles) north of Colombo said.
The Muslims attacked Saturday were part of a convoy organised by Premadasa's supporters and was taking them back to vote in the northern district of Mannar.
One of three election commissioners, Ratnajeevan Hoole, said the authorities failed to provide adequate protection to internally displaced minority Muslims in the multi-ethnic northwest. Officials reportedly reached the spot immediately and cleared the obstructions on the road.
Sources at police said that local military commanders have been warned that any disruption to the election would be reported to courts and offenders prosecuted.
Local media reports have feared that a strong military presence in Jaffna, the heartland of the island's Tamil minority, could influence voter turnout and favour Rajapaksa.
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