At least six soldiers died in an explosives attack perpetrated with the aid of suspected drug traffickers in northeastern Colombia, the army confirmed on Wednesday.

Another 5 soldiers had been injured and one remains lacking after the assault blamed on the Clan del Golfo cartel, the maximum effect within the country But whose chief Dario Antonio Usuga was captured in October.

“Unfortunately the murder of six of our soldiers is confirmed,” said the army in a statement.

The five injured soldiers from the Fourth Brigade “were evacuated by airplane” to a hospital.

“Troops on the ground are continuing to look for one of our soldiers,” added the army.

The attack took place around midnight Tuesday in the Antioquia department.

General Juvenal Diaz told Blu Radio that the Clan del Golfo was responsible for detonating “an improvised explosive device” as a military vehicle was passing.

Antioquia is a key corridor for the transport of cocaine to Colombia’s Pacific coast and on to Panama.

Colombia is the world’s largest producer of cocaine, much of which is smuggled into the United States and Europe.

The Clan del Golfo has increased its attacks on the armed forces since the detention of Usuga, who is known by the alias Otoniel.

Colombia’s authorities have accredited the extradition of Usuga to the United States to stand costs of drug trafficking.

Before his seize, the Clan del Golfo used to export 300 of the 1,010 heaps of cocaine that leaves Colombia each year stated officials.