PHOENIX - Phoenix Police and Silent Witness are now offering a reward to help find two men who robbed a Valley Costco.

The robbery happened at the Costco at the Christown Spectrum Mall on Saturday, March 18, 2017.

Police say two men walked inside the store about 5:50 p.m. and grabbed a shopping cart like any other customers. Then police say one of the men put a large suitcase in the cart and filled it with a security system and speaker system. Detectives say he skipped the registers and went to the exit, where a Costco employee is supposed to check all receipts.

"You can see in the video, he's not even looking at the clerk," said Sgt. Jamie Rothschild, who's with Silent Witness. "It's like he's looking out the door, wondering where his friend is."

Sgt. Rothschild said that's because the other man was waiting outside. Then the one inside the store grabbed the suitcase full of merchandise, ran outside and threw it in a white pick-up truck. Costco workers tried to stop him, and one of the men showed a gun.

"The fact that someone was willing to display a weapon over property and endanger the lives of people who just want to get their property back -- that's why we want to find these guys," said Sgt. Rothschild.

Security cameras captured clear videos and pictures of both men.

If you recognize them, you're asked to call Silent Witness at 480-WITNESS. You can remain anonymous and could receive a reward of up to $1,000.