The Colombian navy and national police were searching Sunday for eight people kidnapped by 20 gunmen who raided a small island off Colombia's Caribbean coast, authorities said.

Also Sunday, soldiers killed 16 members of the Revolutionary Armed Forces of Colombia, or FARC -- Colombia's largest rebel army -- in eastern Antioquia state, the army said.

Since last month, soldiers have been battling an 180-member FARC unit in Antioquia state. More than 50 rebels have been killed and another 21 captured, the army said.

Army spokesman Capt. Luis Enrique Hernandez said the unit, known as the 47th Front, was "on the verge of disappearing" after Sunday's battle.

On Mucura Island, some 300 miles northwest of the capital, Bogota, kidnappers grabbed an 11-year-old boy and bodyguards of businessmen vacationing during the Easter holidays, Navy Capt. Juan Manuel Lesnes said Sunday. The boy had been vacationing with his family.

The motive for Saturday's abductions were unclear.

Nearly 3,000 people were kidnapped last year in Colombia. The country's two main rebel factions carry out hundreds of kidnappings every year for political purposes and use the ransom payments to fund their insurgencies.

Leftist rebels have been fighting Colombian government troops and right-wing paramilitary militias for 38 years. The fighting kills an estimated 3,500 people every year, mostly civilians.