Colombian presidential candidate Miguel Uribe Turbay in critical condition

In a statement, doctors said the 39-year-old senator "barely" responded to medical interventions that included brain surgery after the attempted murder, AP reported.

The attack happened while Uribe was speaking to a small group of people in a park in the Modelia neighborhood.

On Sunday, hundreds of people gathered outside the hospital where he is being treated, praying for his recovery.

Some of them wore rosaries, while others chanted slogans against President Gustavo Petro.

Petro condemned the attack and called for the political use of the incident to be avoided, while some asked the president to tone down his rhetoric towards the opposition.

The incident happened at a time when the political conflict between President Petro and the opposition, especially regarding legislative reforms, was escalating.

Yesterday, the Colombian Senate adjourned its sessions as a sign of solidarity with Uribe, while the opposition parties requested international assistance to ensure conditions of equality in the political process.

The investigation into the attack is ongoing, and the suspect, a 15-year-old teenager, was arrested at the scene.

Videos on social media show the moment the suspect shot Uribe at close range.

Although minors in Colombia face up to eight years in prison for murder, State Prosecutor Luz Adriana Camargo warned of the problem of armed groups recruiting minors.

Uribe's lawyer said he was suing the National Guard for negligence in providing security during his presidential campaign, alleging that the security detail was reduced weeks before the attack, despite previous requests for increased protection.

Petro said that Uribe's security team was reduced from seven to three bodyguards shortly before the attack and that he requested an investigation into the matter.

The motives of the attack are still unclear.

Uribe was wounded during a campaign rally in a public park in the Fontibon neighborhood of Bogota, his Democratic Center party said, condemning the attack, saying it "threatens the life of a political leader... democracy and freedom in Colombia."

A video was published on the Internet showing Uribe being shot in the head, after which the crowd fled in panic.