Six suspects wearing full-faced helmets stormed into a goldsmith shop in the mall at about 5pm, said Selangor Criminal Investigation Department chief SAC Fadzil Ahmat.
The robbers were armed with three pistols, he added.
Police confronted them as they were trying to flee the scene and the robbers fired several shots.
“Police then opened fire on the armed men to defend themselves," he said.
Two of the suspects were shot dead at the scene, while another was injured in the abdomen.
The other three, who were not injured during the incident, were arrested.
The police have seized a semi-automatic pistol, a revolver and an air gun, Fadzil said.
He said police have also recovered the jewellery that were stolen, but that the total value of losses had yet to be determined.
"We believe more than eight suspects were involved. We have identified all of them and are hunting down the remaining suspects.
“Police investigations revealed that they came to the mall on four motorcycles and according to records they have previously been involved in eight robberies in the Klang Valley and Negeri Sembilan," he said, adding that the cases were still being investigated.
Meanwhile, a witness who only wanted to be known as Balasingam said, during the incident he and his friends were at a nearby restaurant.
"We were eating and drinking when suddenly we heard the sounds of gunshots.
"We ran for our lives as the sound was getting closer and louder. I counted there were about seven to eight shots," he added.
Eyewitness Sharmila Ganapathy told the Star Online she heard gunshots from a goldsmith's shop at around 5.15pm, and later saw two men - who looked to be in their 30s or 40s - handcuffed and taken away by police.
Netizens took to social media to post about the incident, with some identifying the shop as Poh Kong, a jewellery retailer.
"I thought who would light firecrackers at this hour ... they were gunshots fired at Atria," wrote Twitter user zhao_wei221. "Robbery at Poh Kong, and two robbers shot dead."
Video posted on Twitter by user Dizzmiz appeared to show two bodies slumped on the road, with two people training their guns on them.