Hector Olivares attends a congressional commission session in Buenos Aires, Argentina. File picture: Nation's Honorable Chamber of Deputies, HCDN via AP

Bogota - Argentinian lawmaker Hector Olivares died Sunday after being shot in Buenos Aires's Congressional Plaza three days earlier, his party confirmed.

Olivares, a lawmaker with the centrist Union Civica Radical (UCR) party, was shot by individuals sitting in a parked car as he was walking near the Argentine Congress with government aide Miguel Yadon early Thursday.

Yadon was also shot and died at the scene.

"Hector Olivares died," UCR said in a tweet late Sunday. "We will demand justice and that the killers serve an effective sentence."

Pedestrians react at the crime scene where Argentine Congressman Hector Olivares was injured and his adviser, Miguel Yadon was killed in an attack near the National Congress in Buenos Aires. File picture: Agustin Marcarian/Reuters

"All those involved in the attack on lawmaker Olivares and Miguel Yadon have been detained, one day after committing the crime, thanks to the impressive work of our community forces," Argentinian President Mauricio Macri said on Friday.

Evidence tent markers dot the crime scene where lawmaker Hector Olivares was injured and another man was killed after they were shot at from a parked car near Congress in Buenos Aires, Argentina, File picture: Natacha Pisarenko/AP

Six people were arrested following the attack, Telam state news agency reported, adding that all six were "part of a gypsy clan."

A police officer stands next to blood on the sidewalk at the crime scene near the National Congress in Buenos Aires. File picture: Agustin Marcarian/Reuters

On Friday, Security Minister Patricia Bullrich said that Yadon appeared to be the target of the attack. "A mafia clan ... killed a person over issues of a personal nature," she said.