Tunisian troops killed a gunman and captured three others on Sunday after they attacked soldiers guarding ballot papers for the country’s presidential vote.

Tunisian troops killed a gunman and captured three others on Sunday after they attacked soldiers guarding ballot papers for the country's presidential vote, the defense ministry said.

The pre-dawn attack targeted a school in the central region of Kairouan where the ballot papers had been stored under army guard.

"The vigilance of the soldiers and the swiftness of their response thwarted this operation and led to the death of a man armed with a hunting rifle and the arrest of three suspects," ministry spokesman Belhassan Oueslati told AFP.

One soldier and one suspect suffered minor wounds, he added.

Oueslati said he did not believe that jihdadists, who had called for a boycott of Sunday's landmark election runoff and threatened to target the political establishment, were behind the attack.

"Generally, the terrorists don't use hunting rifles," he said.

In an Internet video posted Wednesday, jihadists claimed the 2013 murder of two secular politicians that plunged Tunisia into crisis, warning of more killings of politicians and security forces.

The authorities deployed tens of thousands of troops and police to provide polling day security.

Tunisians voted Sunday in the runoff of the first free presidential election in the country's history, the final leg of an at times bumpy four-year transition from dictatorship.

The second round vote pits 88-year-old favourite Beji Caid Essebsi, leader of the anti-Islamist Nidaa Tounes party, against incumbent Moncef Marzouki, who held the post through an alliance with the moderate Islamist movement Ennahda.