Updated: 05:39 AM EDT Suspect Arrested in Wal-Mart Employee Killings Two Workers Shot Dead in Store Parking Lot By MICHELLE ROBERTS, AP GLENDALE, Ariz. (Aug. 24) - Authorities were trying to determine why a gunman fatally shot two Wal-Mart employees gathering shopping carts in the parking lot of one of the retail stores in suburban Phoenix.AP Detectives work the crime scene at the Wal-Mart n Glendale, Ariz. Police said it doesn't appear that the suspect in custody - Ed Lui - knew the victims or had a vendetta against them or Wal-Mart. The gunman also did not appear to have been under the influence of any substance at the time of Tuesday afternoon's shootings, authorities said. "We don't know why he did this. This was barbaric," said Officer Mike Pena, a Glendale police spokesman. "There's no motive at all. It's a random act." Lui, 53, was booked into jail Tuesday night on two counts of first-degree murder. The shootings occurred in the middle of the parking lot, about 75 yards from the store entrance. At one point, a body could be seen in one of the corrals used for collecting shopping carts. Police said Lui drove into the parking lot, got out of his car and allegedly shot each victim several times with a handgun. It does not appear Lui spoke with the victims. The gunman then drove away but was followed by two witnesses who were able to provide license plate numbers that police used to track Lui's car. Pena said Lui was arrested without incident in a retirement community in nearby Peoria. Investigators initially sent a robot to Lui's door, fearing he could still be armed, but he came out with his hands up. After he was captured, Lui was calm at the police station, answering "yes" and "no" questions, according to Pena, who did not immediately know whether Lui had a criminal record. The victims were identified as Anthony Spangler, 18, and Patrick Graham, who was either 18 or 19. Both were from Glendale. Delia Garcia, a Wal-Mart spokeswoman on the scene, said the two young men were collecting shopping carts when the gunfire broke out. She said the store would be closed at least until Wednesday. "This is an extremely tragic situation," company spokeswoman Sharon Weber said from Wal-Mart headquarters in Bentonville, Ark. Authorities initially kept customers inside the store, but they were later allowed to leave. One woman said the store was filled with screaming people who were trying to get out and "it was just pure chaos." Late Tuesday, police had cordoned off the suspect's neighborhood about two miles from the Wal-Mart. Plainclothes officers roamed through the area of stuccoed homes with red-tile roofs and desert landscaping. At the scene of the shooting, police also cordoned off much of the store's parking lot, telling anyone whose car was within a perimeter that they would have to leave their vehicles there. Some of the store's 450 employees could be seen leaving the business Tuesday evening. The company planned to offer help for workers upset by the shootings, Garcia said. The scene of the shooting was about 20 miles northwest of downtown Phoenix. Associated Press Writer Paul Davenport contributed to this report from Phoenix.