Comes as President Juan Manuel Santos seeks to end the mostly drug-related armed conflict wracking the country for 50 years.
At least five police officers were killed and 41 others wounded on Saturday when alleged drug traffickers detonated a bomb at a station in the northern city of Barranquilla, hours after a car explosion ripped through a security post near the border in neighboring Ecuador.
There was no apparent link between the two attacks, but they come as President Juan Manuel Santos seeks to end the armed conflict that has wracked Colombia for 50 years. Much of the violence has been linked to drug-trafficking.
The bombing in Barranquilla was one of the deadliest on security personnel in recent years, casting a pall over preparations for the annual carnival, a major attraction in the bustling Caribbean port city.
Barranquilla police commander Mariano Botero said the bomb detonated as the officers gathered for morning formation.
A police source told AFP that 49 officers were at the site when the bomb exploded. Of those, five officers aged between 24 and 31 were killed and 41 were wounded.
A 31-year-old man was arrested on suspicion of carrying out the attack, according to Attorney General Nestor Martinez.
“We will charge [him] with five aggravated murders... attempted murder, terrorism and use of explosives,” Mr. Martinez told a press conference.
Retaliatory attack by drug-peddlers?
Barranquilla Mayor Alejandro Char quickly blamed drug-traffickers for the attack.
“I do not have the slightest doubt that this is a retaliation” for successful police action against drug-traffickers, he told reporters.
Mr. Botero also suggested that the attack could be in revenge after a police crackdown on local drug traffickers.
Colombia is the world’s top producer of cocaine, and criminal groups have flooded the country's main cities with drugs in a move known as “microtrafficking.”
Mr. Santos blasted the “cowardly attack” on Twitter.
“We will not rest until we find those responsible, my solidarity is with the families of the victims and the wounded,” he wrote.
Joining Mr. Santos was Rodrigo “Timochenko” Londono — the presidential candidate of the FARC, the former guerrilla group which is now a leftist political party — who “vehemently” condemned the Barranquilla attack.
“All our solidarity is for the relatives of the slain police,” he wrote on Twitter.
Mr. Santos reached a historic peace agreement with the FARC -- formerly known as the Revolutionary Armed Forces of Colombia -- in November 2016. That led to the rebels' disarmament and transformation into a political party.
The President, who is set to step down in August, is hoping to reach a similar agreement with the smaller National Liberation Army (ELN) guerrillas.
Ecuador attack
In an apparently unrelated attack in Ecuador, not far from the country’s border with Colombia, a car bomb destroyed the San Lorenzo police barracks around 1:30 am (0630 GMT).
President Lenin Moreno called it a “terrorist act linked to gangs of drug-traffickers.”
The blast slightly wounded 28 people -- both locals and police. Some 37 homes were destroyed, according to the Interior Ministry.
Mr. Moreno declared a state of emergency in the towns of Eloy Alfaro and San Lorenzo, home to some 56,000 people, “in order to boost security for citizens and the border.”
Ecuador is considered a transit country for cocaine produced in Colombia and sold in Europe and the United States. Since Ecuador lacks major drug crops, authorities there fight against gangs that store narcotics.