Leellette D. Rutherford was inside the store Thursday evening when Justin Cudar walked in and began firing without warning, killing a customer and a clerk and severely wounding another employee.
A terrified Rutherford pleaded with the 911 operator to send help as she prayed aloud.
"Please God, there are people dying here," Rutherford, 55, told the operator. "There's blood all over the place."
The tape of the dramatic emergency call was released as authorities and families struggled to understand Cudar's motive.
Police said Cudar, 25, a psychology major at the University of South Florida, may have undergone treatment for paranoia and was being investigated in a road rage incident earlier in the day at the time of the shooting.
His mother last saw him several hours before the shooting when he left their St. Petersburg home and told her he was "going to do some target practice," police Sgt. Mike Puetz said.
There is no known connection between Cudar and the Radio Shack store or any of the employees, police said. Cudar had purchased the Glock .40-caliber handgun legally Nov. 5.
"It appears to be a random and senseless act at this time," police spokesman Bill Proffitt said.
Killed were customer Kenneth Powell, 23, and store clerk Joana Cruz, 19. Another clerk, James Dolan, 30, was hospitalized in critical condition Friday. Cudar shot himself to death; his body was found in the store.
Puetz said Rutherford had dropped to the ground in the fetal position when Cudar, who was standing behind her, started shooting. He said she does not know if he mistakenly thought she had been hit and moved on to shooting others.
Barbara Cudar did not answer her door Friday. Michelle Luciano, a neighbor, said Justin Cudar never showed signs of trouble.
"He was a good kid," Luciano said. "It's just shocking."
Marianne Pasha, a spokeswoman for the sheriff's office, said deputies spoke with Cudar's mother after receiving a report earlier in the day of a driver exchanging hostile glances with two people in a pickup truck, then throwing a steering-wheel locking device through the pickup's window. The frightened victims hid behind a store and called for help, Pasha said.
"His mother said her son had anger-management issues," Pasha said Friday. "I am not sure anyone will know what set him off."
By Sara Kennedy