Borno state governor, Kashim Shettima

Some unidentified gunmen suspected to be Islamist militants attacked the convoy of  Borno state governor, Kashim Shettima on Tuesday on his way from the state capital Maiduguri to the market town of Gamboru for a rally ahead of the presidential election, killing at least three people, official sources said on Wednesday.

The identity of the gunmen was not immediately clear, but the sources said they suspected Islamist groups, such as Boko Haram or Islamic State West Africa Province, which have waged a decade-long insurgency in the northeast. They said the gunmen opened fire at the motorcade transporting the governor.

Two security sources said three people died.

A government and a separate security source said as many as 10 people were killed during the attack.

The governor’s spokesman could not be reached for comment.

As Voters in Nigeria go to the polls on Saturday to elect a new president. Incumbent Muhammadu Buhari is seeking a second term in office but faces a tight contest from main challenger, Atiku Abubakar, a businessman and former vice president.