Manila: At least seven people were killed while a presidential aide survived an ambush during mid-term elections in the Philippines on Monday, authorities said.

All of the deaths were in the violence-plagued south, where a separatist insurgency has been waged for decades and political warlords employ private armies.

In the most violent incident, supporters of rival candidates for mayor on a small southern island in the Sulu archipelago opened fire on each other, leaving three dead, local police and a military spokesman said.

Unidentified gunmen opened fire on a vehicle carrying voters on the nearby island of Jolo, killing the driver and wounding four passengers, said provincial police chief senior superintendent Antonio Freyra.

Three supporters of a local candidate were killed and eight wounded by unidentified gunmen in another attack in Zamboanga del Sur, a separate province in the south, the regional military chief said.

Meanwhile, President Benigno Aquino’s political adviser, Manuel Mamba, escaped unharmed after his convoy was attacked in the northern town of Alcala, presidential spokesman Ramon Carandang said.

He said Mamba was in the area to support one of his brothers, who was a candidate for provincial governor under Aquino’s Liberal Party.

Mamba, talking to radio station DZMM in Manila, said he saw his brother’s rival brandishing an AK-47 assault rifle as his convoy passed on the national highway. He said he then heard shots that hit one of the vehicles in the convoy.

More than 60 people had already been killed in the lead-up to the elections, in which more than 18,000 positions — from town mayors and provincial governors to members of the nation’s legislature — are being contested.