MANILA, Philippines — Gunmen ambushed a caravan of political supporters and journalists on their way to file election papers, killing at least 24 people in a massacre considered shocking even for a region notorious for violence between rival clans.
The National Union of Journalists of the Philippines said at least 10 local reporters were part of the convoy, but police spokesman Leonardo Espina said Tuesday that authorities had identified the remains of only one so far.
Their newspapers and radio stations have not been able to reach any of the journalists, raising fears that they were killed. If confirmed, it would be the “largest single massacre of journalists ever,” according to Paris-based Reporters Without Borders.
“Covering the news has always been dangerous in the Philippines, but the wanton killing of so many people makes this an assault on the very fabric of the country’s democracy,” said Bob Dietz, Asia program coordinator for the Committee to Protect Journalists in New York.
The president’s office termed the attack the worst political violence in recent history. Many among the 24 dead were women, including two lawyers, Espina said.
Police said the convoy of 40 people was going to register Ismael Mangudadatu to run for provincial governor when they were stopped by some 100 gunmen and taken to a remote mountainous area.
Soldiers and police later found 21 bodies, including those of Mangudadatu’s wife, Genalyn, and his two sisters, sprawled on the ground or shot in their vehicles about three miles from where they were ambushed, military spokesman Lt. Col. Romeo Brawner said.
Mangudadatu, deputy mayor of the town of Buluan and a fierce political rival of the current governor of Maguindanao province, said his wife called him by mobile phone shortly before she and her entourage were abducted.
“She said ... they were stopped by 100 uniformed armed men ... then her line got cut off,” he said.
The five vans being used by the group were found abandoned. The army and police were searching for the 16 people who were missing, Brawner said, adding that troops were looking for more bodies in areas that appeared to have been recently dug up.
A backhoe was apparently used to bury the bodies, said army commander Lt. Col. Rolando Nerona.
While candidates are typically part of the festive caravans that travel to file election papers, Mangudadatu had sent his family and supporters because he had received death threats. Most of those on the caravan were women because it was thought they would be safer than men.
The identity of the attackers was unclear, but the military said it believed the motive for the attack was political. National police chief Jesus Verzosa placed a police chief in the area under investigation and relieved him of his duties.
The Mangudadatus blamed their rivals, the powerful Ampatuan family, which has ruled since 2001.
“They don’t want us to file our candidacy in Maguindanao. It’s like they hold a franchise, they want everything,” said Mangudadatu’s brother, Jong, the mayor of Buluan.
The Ampatuans were unreachable for comment.
The region, among the nation’s poorest and awash with weapons, has been intermittently ruled by the Ampatuan family.
Andal Ampatuan, the family’s patriarch and governor of the province, has survived half a dozen attacks on his life. He has blamed those assaults, one of which claimed a son, on Muslim rivals from the separatist Moro Islamic Liberation Front, which has been fighting for a greater autonomy in the southern Philippines for decades.
Government officials called the attack political and said it was not thought to involve the front.
President Gloria Macapagal Arroyo ordered her defense chief, Norberto Gonzales, to fly to the south Tuesday to oversee military action against the attackers and secure the area.
The coastal province of Maguindanao is part of the Autonomous Region in Muslim Mindanao, which was created as part of a 1996 peace agreement with a large Muslim rebel group.
Philippine elections are particularly violent in the south because of the presence of armed groups, including Muslim rebels fighting for self-rule in the predominantly Roman Catholic nation, and political warlords who maintain private armies.
The last elections in 2007 were considered peaceful, even though about 130 people were killed.
The decadeslong Muslim insurgency has killed about 120,000 people since the 1970s. But a presidential adviser, Jesus Dureza, said the massacre was “unequaled in recent history.”
“There must be a total stop to this senseless violence,” he said, recommending a state of emergency be imposed in the area to disarm all gunmen. “Anything else will not work.”
Rebel spokesman Eid Kabalu said the guerrillas had nothing to do with the massacre, which he described as election-related.
Army troops went on full alert in Maguindanao to prevent retaliatory killings, regional military commander Maj. Gen. Alfredo Cayton said.
According to information provided by the Committee to Protect Journalists, there have been attacks on media buildings that resulted in more deaths, but not all of those killed were journalists. For example, five journalists and six other employees of satellite TV channel Al-Shaabiya were killed in attack on their offices in Baghdad in 2006.

Associated Press writers Jim Gomez and Teresa Cerojano contributed to this report.