LAKEWOOD, Wash. -- The robbery of a Lakewood Wal-Mart that left an armored car guard dead was likely an inside job involving an employee of the store, police sources tell KIRO 7 Eyewitness News.

A store employee was among two people arrested Tuesday night in the investigation, police sources said. When reporter Jeff Dubois asked workers at the store if she worked there and was told "she is not here today."

The man accused of firing the fatal shot in the robbery was arrested Wednesday morning, police sources said. The sources said Calvin Finley was arrested at a motel in nearby Fife.

Meanwhile, officers from multiple police agencies and the FBI continue searching for the other robber seen on surveillance camera images immediately after the shooting and robbery.

RAW VIDEO: Wal-Mart Evacuated After Fatal Heist
SLIDESHOW: Armored Car Guard Robbed, Shot In Lakewood Wal-Mart

A single bullet killed a guard and wounded a male customer during the Tuesday afternoon robbery in Lakewood.

The robbers grabbed a money bag from the guard and drove off after the shooting. Their stolen white getaway car was later found abandoned in Tacoma.

Killed was Kurt Husted, 39, a 16-year veteran of Houston-based Loomis armored cars, company spokesman Pat Flaherty said.

Husted's family issued a statement, saying they deeply mourn his loss.

"He was a wonderful, caring person whom we loved deeply and will miss forever. He was also a very private person," the statement said.

Husted was shot outside a branch of Anchor Bank located inside the Wal-Mart.

"As he was coming out of the bank, he was shot in the head," said Lakewood police Lt. Heidi Hoffman.

The guard had been wearing a bulletproof vest, Flaherty said. He said Husted was not married.

The same bullet also injured a male customer who was hit in the shoulder, police said. He was with a child who was in a shopping car. The child was uninjured and the man's injury was not life-threatening, she said.

The customer, who was not identified, was taken to Tacoma General Hospital.

There was money in the bag the robbers grabbed, Hoffman confirmed, but she declined to say how much it contained.

In a statement, Wal-Mart officials said their thoughts and prayers were with those "victimized by this tragedy. We appreciate the quick response of local authorities, and we are working with them in their investigation."