Surveillance footage at the Hong Kong Nails salon appears to show two men entering the store Friday with pistols drawn, The Miami Herald reported Saturday.
The footage didn't show the shooting, but the men can be seen leaving with what appears to be a woman's purse.
Police said the men shot and killed 10-year-old Aaron Vu, and shot and critically wounded Aaron's father, Hai Nam Vu, 42. Hai Nam Vu's wife, Lynn, and other workers were at the salon at the time of the incident.
Police said they were able to get a clear image of what one of the gunmen looks like using the surveillance footage. Authorities are also looking for the truck the men sped away in, a black Dodge Ram pickup.
"There was a lot of traffic along there, and somebody had to have seen that truck going out of there at a high rate of speed," said Miami-Dade detective Alvaro Zabaleta. "And somebody has to recognize the photo of the one gunman. It's an incredibly clear image."