At least three police officers were killed and 14 wounded on Saturday by an early morning bomb attack outside a police station in Colombia's coastal city of Barranquilla, authorities said.
The attack targeted the officers as they gathered in the San Jose neighborhood to receive their orders for the day, metropolitan police commander Brigadier General Mariano de la Cruz Botero told journalists.
"We think it could be retaliation by these groups who have recently been greatly impacted," Botero said in comments broadcast by Caracol Radio, referring to crime gangs active in the port city.
Botero said one person had been arrested in connection with the bombing, and that police suspect others were involved.
He said the person in custody could be the individual who placed and then triggered the device, according to the police's initial analysis.
President Juan Manuel Santos sent his condolences to the families of those killed and injured, and said on Twitter that the government would not rest until those responsible were brought to justice.
Colombia has myriad crime gangs, some which operate across large swaths of rural territory and others in major cities. Many are involved in the production and trafficking of cocaine, largely to the United States and Europe, as well as extortion and other crimes.