An ambush by alleged FARC guerrillas in northern Colombia killed a senior police officer and injured five people.

Major Felix Antonio Jaimes, who served in the highway patrol in the province of Antioquia, was killed by a concealed explosive device on the Troncal Occidental highway, between the city of Medellin and the Caribbean Coast.

Jamies was called to the scene after guerrillas had burned three vehicles. Two police officers were also injured by the bomb which killed Jamies, while three people were injured in the earlier incident.

Colombian President Juan Manuel Santos called the attack “an act of terrorism” and a “sign of weakness” from the Revolutionary Armed Forces of Colombia (Fuerzas Armadas Revolucionarias de Colombia – FARC), who he said are becoming ever more desperate.

The leaders of FARC’s 36th Front, known by the aliases “Anderson” and “Emilio Chaqueto,” have claimed responsibility for the attack. The governor of Antioquia has offered a reward of up to 500 million pesos (around $280,000) for information leading to their arrest.

The attack is the latest in a string of attacks in Antioquia, where kidnapping and illegal roadblocks have increased in frequency of late. Despite their position of weakness, the FARC promised earlier in the year to double their activity in 2011.