At least four people were killed and another 18 were injured when a car bomb exploded in an exclusive neighborhood in Colombia's third-largest city, Medellin.
It was the second car bomb to explode in less than 15 days in Colombia, which is torn by a 37-year-old war that has killed 40,000 civilians in the last decade.
"Unfortunately, the toll so far is four people dead and 18 injured," Medellin Police Chief Gen. Jorge Daniel Castro, told Reuters.
Television showed images of people, hurt by glass fragments and covered in blood, being hustled away in ambulances and other vehicles. Firefighters rushed to the scene and sprayed water on a twisted vehicle believed to be the car bomb.
The explosion occurred shortly after 10 p.m. local time in a popular public park in the upscale sector of El Poblado in the northwestern city of Medellin.
On May 4, a powerful car bomb ripped through a luxury hotel in Cali, Colombia's second-largest city, injuring 32 people.
Medellin Mayor Mr Luis Perez Gutierrez said the attack could be linked to a recent police crackdown on the city's notorious criminal gangs. "We've had a lot of recent successes against criminal gangs. It wouldn't be surprising these bands, out of desperation, are behind the attack," he said.
Medellin, the industrial hub of Colombia, is famous for being the city where former drug boss Pablo Escobar built his multimillion dollar empire before he was gunned down by an elite police unit on a Medellin rooftop in 1993.
Although the Medellin drug cartel has been dismantled, the city is still corroded by drug-related violence.
Colombia, the world's No.1 producer of cocaine, is torn by a drug-fueled war that pits leftist guerrillas against outlawed right-wing militias and the army.
No group has claimed responsibility for Thursday's attack.