CLANTON (AP) — Pit vipers called copperheads have bitten four children in Alabama in eight days.

Al.com reports that a 7-year-old boy was bitten on a toe Thursday night in one Birmingham suburb, and an 8-year-old girl was bitten Sept. 6 in another suburb.

Between those dates, two 12-year-old girls were bitten during a nature walk behind a Chilton County high school, and one of them was being treated Friday, WRBC-TV reported .

Anna Claire Pledger’s mother, Maryann Pledger, told the newspaper that once her daughter realized she’d been bitten, she protected her 5-year-old brother and 6-year-old sister, yelling, “Snake! Babies run! Run to Daddy!” over and over.

Anna Claire spent several days in the hospital, receiving 21 vials of antivenin, her mother said.

Birmingham is about 45 miles (72 kilometers) north of the community of Isabella, where the 12-year-olds were bitten.

Dr. Eric Yates, an emergency room physician at Grandview Medical Center, told WRBC that the number of snake bites treated there this year is about average.

“Copperheads can be found throughout the state of Alabama and are quite common in some areas,” David Steen, an assistant research professor at the Auburn University Museum of Natural History told Al.com . “I think it is safe to say that we see only a small fraction of the copperheads we are near as they are highly camouflaged and stay still to avoid predators.”

They may be encountered more often in the fall, when they may be seeking mates or places to hibernate, he said.

The U.S. Centers for Disease Control estimates that venomous snakes bite 7,000 to 8,000 people a year, causing about five deaths annually.

Copperheads are rarely aggressive, and tend to freeze when they get spooked, according to the CDC.

Copperhead venom is generally considered milder than some other venomous snakes in the U.S. Steen said it’s rare that a copperhead bite would kill humans.

“Many if not most venomous snake bites happen when attempts are made to capture, kill, or harass snakes, but occasionally a snake might strike if we accidentally get too close,” Steen said. “The risk of snake bite can be minimized by learning about the snakes in your area, watching where you put your hands and feet, and wearing close-toed shoes when walking around natural areas.”