HOUSTON -

Robberies at fast food restaurants have kept investigators in Houston and Harris County busy this week.

A robbery at a Subway at MLK and the South Loop turned deadly Tuesday evening when a customer was shot and killed during a struggle with the suspects. Police identified the victim as 36-year-old Christopher McGrew.

Since Monday, Local 2 has told you about six robberies at fast food restaurants in Houston and Harris County, including one at another Subway location at Little York and Antoine. A robbery at Fantastic Donuts and Croissants on Tuesday led to a shootout between suspects and the store's owner. He was rushed to the hospital after he was hit by gunfire.

Though it's too soon to know how many of the robberies may be related, Houston police say there has been an uptick in fast food robberies during the last couple of months. They're reminding the public to always be on alert.

"If they have a weapon, then you have to go ahead and submit because your life is the most important thing at that point," said Senior HPD Officer Jesse L. Martinez.

If you do find yourself in a situation involving robbery suspects, they advise you to stay calm and avoid sudden movements.

Click here to read more crime prevention tips from Houston police.