Philippine police said they have identified and are hunting eight gunmen who killed 13 people in an ambush on a mayor, an attack that cast a pall of fear over upcoming elections.
Police are also considering expanding security measures, amid fears of further violence from politicians' private armies and communist guerrillas ahead of the May 13 mid-term polls.
Gunmen opened fire on a truck carrying Mayor Abdulmalik Manamparan, 62, and his supporters in the troubled southern Philippines late Thursday, the deadliest in a string of violent incidents that have marred campaigning.
The mayor was injured and his daughter and granddaughter killed.
"We have already identified the suspects as a longtime enemy of the Manamparan clan," said provincial police chief, Senior Superintendent Gerardo Rosales.
They were followers of a Muslim clan that had a family feud with the Manamparans and officers were preparing to arrest them, he said.
Meanwhile, police arrested 11 communist guerrillas just outside Manila late Friday as they were distributing "permits to campaign" to politicians, a provincial police director said.
Senior Superintendent Joel Orduna said police seized five rifles, a shotgun and three pistols from the rebels of the New People's Army in Dona Trinidad town.
The military has previously accused the NPA of extorting money from politicians in exchange for issuing "permits" that will allow them to campaign unmolested.
A police tally now lists a total of 46 deaths from at least 48 violent incidents reported since the start of the campaign in February.
Political violence from rebels, hired thugs of politicians and other armed groups have long plagued elections in the Philippines despite security precautions.
More than 18,000 posts are at stake in the May 13 elections, from town mayors and governors to members of parliament.
National police spokesman Chief Superintendent Generoso Cerbo said the police leadership had already identified 15 "priority provinces" for tighter security due to the possibility of election violence.
"We are entertaining the idea of (adding) other provinces," he said in an interview with ABS-CBN television.