Did you know if you're close enough to hear thunder, you're close enough to be struck by lightning?

It's true.  That's why the motto for this week is "When Thunder Roars, Go Indoors."

The first full week of Summer is always "Lightning Awareness Week" as proclaimed by the National Weather Service.

An average of 55 Americans are killed each year by lightning.

In fact, there have even been cases where people have been struck by lightning from a storm 10 to 12 miles away.

According to a lightning specialist with the National Weather Service, most of those killed were taking part in leisure activities at the time they were struck.

Most were outside - either fishing, camping or boating.

ABC News has more on what you can do to protect yourself.