MILAN (AP) — Heavy rain flooded a gorge filled with hikers Monday in the southern region of Calabria, killing at least eight people, Italy's civil protection agency said.

It said the dead included four men and four women.

The head of civil protection in Calabria, Carlo Tansi, told Sky TG24 that 12 other people, including a 10-year-old boy, were brought to safety in the flash flood in the Raganello Gorge, a popular aquatic trekking spot. The boy suffered hypothermia and was among six people who were injured, the agency said.

It was unclear how many people were missing but at least three groups of hikers were said to be in the gorge.

"The problem is we don't know how many people were knocked over by this flood," Tansi said. "This is a split in the terrain that is very tight and high. Imagine nearly a kilometer (half a mile) in height. And just a few meters (yards) wide. Imagine people who were in this hole."

Tansi said it would take hours to know the possible toll.

The gorge on the eastern side of the Pollino National Park boasts aquatic trekking along the stream that cuts through the massive rock, where hikers pass by water falls, water tubs and natural slipways, according to a website. The 12-kilometer- (71/2-mile-) long gorge is broken down into three sections, the upper, mid and lower canyons, with hikes averaging between 2 ½ and 3 ½ hours. Guides include spelunkers and rescue instructors.