A police officer examines the scene of the attack in Sri Lanka's capital Colombo where gunmen sprayed bullets into a crowd of 500 to 600 supporters of the United National Party (UNP) on July 31, 2015
Colombo (AFP) - Sri Lankan police appealed for information Saturday to track down four gunmen who opened fire at a ruling party rally in the capital, killing a woman and wounding 12 other people.
Several teams of detective were assembled Saturday, a day after the daring attack on Finance Minister Ravi Karunanayake's campaign rally for the August 17 parliamentary elections, police spokesman Ruwan Gunasekera said.
The minister who escaped unhurt accused the opposition United People's Freedom Alliance (UPFA) of carrying out the attack, a charge denied by the party.
"We are investigating the motive for the attack," the police spokesman said adding that no arrests had been made 24 hours after the attack in a commercial area of the capital.
Friday's shooting was the worst attack against a campaign rally in the run up to this month's election.
The 52-year-old finance minister is one of the most senior members of the UNP, which backed former president Mahinda Rajapakse's successor Maithripala Sirisena in January's presidential election.
He had initiated several investigations into alleged fraud by members of the Rajapakse regime.
But Rajapakse's UPFA denied any involvement, alleging an "internal clash" within the ruling party.
This year's campaign had been largely peaceful and local election monitors expressed surprise at Friday's shooting.
Almost all previous elections have been marred by allegations that government workers colluded with the ruling party to give them an undue advantage.
Ahead of January's presidential poll, election chief Mahinda Deshapriya had ordered police to shoot anyone trying to disrupt the vote.
The presidential election passed off relatively peacefully, although one Sirisena supporter was killed in a drive-by shooting.