TISHOMINGO, OK -- Rescuers have been responding to more emergency calls at a Johnston County swimming hole the past few days than they did all last summer. It's all due to a seemingly fun, but dangerous summer activity – Cliff diving.

But jumping into any body of water that you're not familiar with can be dangerous. And emergency workers said they're concerned about the growing number of injuries on Pennington Creek in Tishomingo. In the past three days they’ve responded to four serious injuries near the dam.

"We have a few people that decide they wanted to push the limits,” said Kenny Power, the director of the Johnston County Ambulance Service.

Rescuers said it all starts when people get a boost up onto the top of a pump house near the dam, at least 50 feet above the water.

"Individuals are getting up, running off, jumping into the water here at the corner of the dam, and they're not sure where the rocks are and they're catching the rocks just underneath the water,” said Power.

When they take the plunge, jumpers aim for a spot that’s normally about eight to 10 feet deep. But if they miss, then it’s as shallow as four feet and there are rocks below. It’s a risky activity.

But 19-year-old Dustin Zertuche said he's been jumping here at Pennington Creek for years, including rocks, the dam and the pump house roof.

"I’ve jumped off all of it. It's fun, I like the adrenaline rush,” said Zertuche.

While Dustin said he's never been seriously hurt, he can't say the same for others.

"I was here the other day when that guy got hurt right here along his face,” he said.

It was Monday when two people jumped off the pump house roof and landed in the wrong spot. Tishomingo firefighters say one man broke his leg and was possibly paralyzed from the waist down. Another man also was injured when jumped, landed on his back and hit his head on the rock.

Both were knocked unconscious from the impact and had to flown by helicopter to nearby hospitals.

"Every year we usually have one or two, this year I want to say it's been in the extremes. Especially in the last three days we've had four calls, hopefully we won't have to come down here anymore,” said Power.

The string of injuries has rescuers worried and they hope everyone will use caution and common sense when it comes to this swimming hole, or any other natural body of water.

"To me, getting up that high and jumping in the water is crazy anyway, I wouldn't do it. But the people get up there, they always want to do something to show off for somebody else and it's just not safe,” said Power.

The pump house is also a city building, and jumping off of it or even the dam is against city ordinance. There are signs posted around the swimming hole with warnings, but enforcing those rules can be difficult, especially on the weekends when there can be nearly a hundred people at the swimming hole. Rescuers say they don't want to shut it down, and urge swimmers to put safety first.