MANILA: Philippine President Gloria Macapagal Arroyo placed two southern provinces under a state of emergency Tuesday after gunmen killed at least 24 people in an attack on an election caravan.

The emergency measures, including checkpoints and random searches by authorities, will remain in place until the president is confident that law and order have been restored in the region, Arroyo spokesman Serge Remonde said.

"No one will be untouchable," he told reporters, as officials promised to make arrests in the country's worst election massacre.

Remonde called the killings "unconscionable."

Troops were finding a couple of bodies every hour or so, and officials were still trying to get the exact number of family members, political supporters and journalists who were intercepted by about 100 gunmen Monday and taken to a remote mountainous area, said Interior Secretary Ronaldo Puno.

"We're hopeful that some people escaped, and we're hoping to find them alive," he said.

Police said the convoy of about 40 people was going to register Ismael Mangudadatu, vice mayor of Buluan township, to run for provincial governor when they were stopped.

Soldiers and police later found 24 bodies, including those of Mangudadatu's wife, Genalyn, and his two sisters, sprawled on the ground or shot in their vehicles about three miles (five kilometers) from where they were ambushed, police spokesman Leonardo Espina said.

Mangudadatu, who did not take part in the convoy of vehicles, said said Tuesday that four witnesses had told him the caravan was stopped by gunmen loyal to his fierce political rival and the current governor of Maguindanao province, Andal Ampatuan Jr.

He refused to name the witnesses or offer other details.

"It was really planned because they had already dug a huge hole (for the bodies)," Mangudadatu said.

The National Union of Journalists of the Philippines said at least 10 local reporters were part of the convoy. Espina said they identified the remains of at least one journalist and the head of a small private TV station, UNTV, said investigators told him they found the bodies of his correspondent and cameraman. A driver and an assistant cameraman were still missing, Jay Sonza said.

If confirmed, it would be the "largest single massacre of journalists ever," according to Paris-based Reporters Without Borders.