A FARC attack against Colombian marines in Puerto Leguizamo, in the southern department of Putumayo, left four injured and five missing, according to the armed forces, reports RCN radio.
According to a statement from the navy, the incursion, an explosive charge detonated by the guerrillas, took place at approximately 8AM Monday.
The four injured marines have been evacuated, while a mission to locate and recover the missing five is underway.
This attack comes at a sensitive time after the rebel group failed on Sunday to deliver two hostages whose release had been promised.
The failure of the operation has been blamed on the FARC for providing the wrong coordinates for the release site of the two men, Salin Sanmiguel and Guillermo Solorzano.
Negotiations to carry out the final phase of the release mission are currently taking place between the government and the Red Cross after the government stated Monday that it had suspended the mission.