Bogota, Colombia (CNN) -- The death toll from a powerful car bomb Wednesday morning in Buenaventura, Colombia, rose to six as the day went on, with at least 42 people wounded, authorities said.
The explosion occurred in the town center, near City Hall and the regional attorney general's office, causing panic and chaos among nearby residents. A local hospital declared a state of emergency, media reported.
Images on CNN affiliate Caracol TV showed mangled vehicles, one with an engine next to it on the sidewalk. Buildings also showed significant damage.
The TV images also showed residents carrying off wounded people.
There were no immediate claims of responsibility or a motive.
"It was a very powerful explosion," said Luz Morales, a reporter for Caracol TV who witnessed the blast.
After the bomb went off, "I couldn't hear anything, I couldn't see anything," she told CNN en Español.
Gen. Freddy Padilla, commander of Colombia's armed forces, identified four of Wednesday's six victims as civilians and one as a policeman. The identity of the sixth was not immediately known.
Padilla said he suspects the bomb was planted by the Revolutionary Armed Forces of Colombia, or FARC.
The Marxist insurgent group has been weakened during the presidency of Alvaro Uribe, but has been fighting the Colombian government for more than 45 years. FARC guerrillas were suspected in a recent incident in Buenaventura in which seven tractor-trailers were set on fire on the main highway connecting the port to the rest of the country.
Colombian Deputy Attorney General Guillermo Mendoza said he suspects drug traffickers.
"My first thought is that is an act by drug trafficking groups that operate in this area," he said. "It could be a confrontation between rival drug groups or a retaliation against the regional attorney general's office."
The bomb was inside a Mazda 323 hatchback, he said.
Buenaventura is Colombia's largest seaport, handling approximately two-thirds of its international imports and exports.
CNN's Karl Penhaul and Journalist Jorge Asdrubal Garcia Romero contributed to this report.