A car bomb exploded this Friday near an air base in Cali, Colombia, killing five people and injuring dozens more.

A truck bomb exploded Thursday in Cali, Colombia's third-largest city, near an air base, killing at least five people and injuring 36, the mayor said, attributing the attack to "narcoterrorism." In June, a series of armed attacks and car bombs near police stations killed seven people, five civilians and two police officers.

"A bomb was detonated" near the Marco Fidel Suarez Military Aviation School, on a northern artery in the city of 2.2 million people, police initially reported. Announcing the attack's death toll to the press, Cali Mayor Alejandro Eder expressed regret that "Cali has once again been the victim of a narcoterrorist attack."

Alejandro Eder announced an immediate ban on truck traffic in his city, fearing further attacks, and offered a $10,000 reward for information to the police. Images circulating on social media show several people lying on the ground being treated by emergency services, a truck on fire, several damaged vehicles, and numerous windows blown out.

"So many people hurt"

"There was a huge explosion near the air base," witness Hector Fabio Bolanos, 65, told AFP, claiming to have seen "so many injured people" on the ground.

"There were deaths among people passing along the avenue," another witness, Alexis Atizabal, 40, told AFP. He was in his badge-making workshop at the time of the explosion, whose windows, he said, shattered without causing any injuries. Several buildings and a nearby school were evacuated.

Regional Governor Dilian Francisca Toro declared it a "terrorist attack." "Terrorism will not defeat us," she said. Authorities have not specified which of the armed groups based in Colombia was behind the bombing.

Attack on a helicopter

A splinter group of the former FARC guerrilla group, the Central General Staff (EMC), claimed responsibility for the series of attacks in June. Also on Thursday in the northwest, eight people were killed and eight others injured in clashes and a drone attack on a police helicopter.

A police official told AFP that the attackers had "harassed" a group of people tasked with eradicating coca leaf plantations. They also used a drone to attack one of their helicopters, which crashed to the ground. Images shared on social media showed the helicopter flying over the area, followed by a detonation and its fall.