HILTON HEAD ISLAND, S.C. (CBS Local) — At first she thought it was a giant rock. Then it moved.

Tanya Miller was out on a bicycle ride and walk Wednesday with her golden retriever/Labrador mix, Shiloh, in Shipyard on Hilton Head Island.

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“I saw this big black thing stand up,” she told The Island Packet. “I thought it was a rock.”

Instead, it was a 12-foot-long alligator sunning itself on the banks of a nearby lagoon.

Miller, 27, and Shiloh took off running in the opposite direction.

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“What are you running from?” people asked as she passed them by for safety. They soon saw for themselves and took off with her. Everybody, including Shiloh, made it to safety without any injuries.

When she reached a safe distance, Miller started to record video of the gator crossing the bike path.

“I’m used to seeing maybe one on a bike ride,” she said. “This morning we saw probably 12 gators.”

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Miller’s gator sighting wasn’t the first on Hilton Head Island this week. Alligators are extremely active during mating season, which runs from early April until early June, according to the Florida Fish and Wildlife Conservation Commission.