FARC guerrillas killed 12 Colombian soldiers Monday and wounded four others in an attack in a rural area in northern Colombia, near the Venezuelan border.
"Unfortunately we have received reports of 12 soldiers dead and four wounded," said Yusti Maria Lopez, a security official in Maicao, the capital of the department of La Guajira, to Agence France-Presse.
According to BBC New, the Colombian army was still trying to find out if any rebels or other soldiers had been killed. Venezuela has beefed up border security.
More from GlobalPost: FARC rebels kill 8 in Colombia attacks
Venezuelan President Hugo Chavez responded to the attack on state television, saying the extra troops are to ensure no rebels pass into his country's territory, reported the Associated Press.
"We are not going to permit irregular groups of whatever stripe to use Venezuela as a place to camp, train or attack forces of other countries, in this case Colombia," Chavez said, according to the AP. Chavez also said he had spoken about the attack with Colombian President Juan Manuel Santos.
Chavez has been accused by previous Colombian governments of harboring FARC guerrillas, but has vehemently denied the claim, said BBC. Monday's attack took place in a remote and mountainous area, which is home mostly to ethnic indigenous populations.
More from GlobalPost: French journalist kidnapped in Colombia