Hundreds of fighters from three rebel armies united to attack a village in western Colombia, officials said Sunday, offering new details in the bold assault that killed at least five police officers.

At least six police officers were kidnapped, and at least 27 others were missing, possibly abducted as well.

The pre-dawn assault Saturday in the village of San Marino reportedly included fighters from Colombia's second largest rebel group, the National Liberation Army, which began exploratory peace talks with Colombia's government in Cuba on Friday.

The attack was not expected to have a major effect on the talks, however, because a cease-fire was not a condition for the negotiations.

The fighting appeared to signal a new tactic in which various guerrilla factions unite for an attack, said Gen. Alonso Arango, deputy chief of the National Police.

The attack also involved the Revolutionary Armed Forces of Colombia, or FARC, and the lesser known Revolutionary Army of Guevara, he said. It came despite the death of six FARC rebels in clashes with ELN earlier this week in another part of the country.

Saturday's attack started with some 500 rebels encircling San Marino, about 170 miles west of Bogota, said Gen. Alonso Arango, deputy chief of the National Police. Outgunned police battled the rebels as they entered the town, he told Caracol Radio.

The fighting lasted about six hours before army reinforcements arrived in helicopters and the rebels retreated into the jungle, Arango said.

Earlier reports indicated that dozens of rebels were involved, but Arango said there were probably about 500.

"There was a huge concentration of rebels in this attack," he said.

The talks in Cuba are aimed at laying the groundwork for formal peace negotiations.

The government is likely to push the ELN to agree to a cease-fire as a condition for such formal talks, a Peace Commission official said on condition of anonymity because she was not authorized to be quoted by name. The ELN's reported role in Saturday's attack was unlikely to undermine the talks, she said.

The attorney general's office said five police officers were killed and six were kidnapped. Arango said the 27 other missing officers may be hiding, though he did not rule out the possibility they had been abducted.

Witnesses said at least four police officers and four civilians were injured.

The 12,000-strong FARC and 3,500-member ELN have been fighting for more than four decades to overthrow the government in the name of redistributing wealth in this country of 44 million people. The groups, both on a U.S. list of terrorist organizations, are also involved in drug trafficking and kidnapping for ransom.

The third group involved in Saturday's attack only operates in the Choco region. Its size is unknown.

President Alvaro Uribe launched a military offensive against the rebels three years ago, leading to a drop in homicides and kidnappings. But the groups remain a potent force, staging surprise attacks in remote parts of the country.

The FARC has killed more than 30 police officers in remote towns in the past three months, and National Police chief Gen. Jorge Daniel Castro warned in October that the rebels have a "macabre plan" to kill small-town police because they are easy targets.

Aside from those kidnapped Saturday, the FARC is holding 59 police officers and three Americans, hoping to exchange them for rebel comrades in prison.

The government this week accepted a proposal from European mediators on where talks for such a swap could be held. The FARC so far has not responded.

Separately, a car bomb killed one person and injured seven late Saturday on a highway in oil-rich eastern Colombia, Arauca Governor Julio Enrique Acosta told RCN Radio. Five Colombian soldiers were among the injured, he said. The bombing bore the hallmarks of the FARC, the governor added.