Thousands of Colombians dressed in white poured into the streets to protest against terrorism after a car bombing at a Bogota police academy killed 21 people and left dozens more wounded.

Amid heavy security and loud chants of “down with the terrorists” and “no more violence”, the crowd marched to Plaza Bolivar on Sunday.

They were greeted by President Ivan Duque, who donned a green police cap for the victims of Thursday’s attack, the deadliest in 15 years in Colombia.

Colombia Bombing
Thousands of people in Bolivar Square (Fernando Vergara/AP)

Young and elderly demonstrators alike spontaneously embraced a large number of the police officers lining the march route.

“We want you to know you’re not alone,” said Jenny Buitrago, 32, who dressed her three young children as police officers in a show of solidarity.

Authorities have attributed Thursday’s bombing to the National Liberation Army (ELN) – the last major guerrilla group following a 2016 peace deal with the Revolutionary Armed Forces of Colombia.

Mr Duque has asked Cuba to arrest 10 rebel commanders who had been living on the communist-governed island with his permission in a fading attempt to jump-start stalled peace talks.

Cuba, which condemned the bombing, has pushed back, saying it is obliged to follow the protocol signed by Mr Duque’s predecessor allowing the negotiators to leave the communist-run island in the event of a rupture in talks.

Colombia Bombing
Colombia’s President Ivan Duque and Vice-President Marta Lucia Ramirez (left) take part in the march (Fernando Vergara/AP)

Sunday’s nationwide marches were promoted as a non-partisan show of unity against violence.

But the outraged people who showed up in Bogota shouted conservative, law and order slogans and showed little interest in preserving what was left of a peace process with the ELN that began in 2017 under the mediation of Cuba, Norway, Venezuela and Chile.

With the political fallout in the balance, authorities have been making steady progress in their investigation of the attack, which recalled some of the bloodiest chapters of Colombia’s recent past.

Within 24 hours of the attack, police arrested a man, Ricardo Carvajal, who they say showed up on intercepted phone calls boasting of having participated in the blast.

Authorities are investigating whether Carvajal is the unidentified man seen on security cameras descending from a 1993 Nissan pick-up less than 10 minutes before it exploded at the General Santander police academy loaded with 80kg of Pentolite.