FRESNO COUNTY, California. (KSEE) – As it warms up this week, some may be more tempted to head to the lakes and rivers. Officials are continuing to urge families to be vigilant, especially with children.

Fortunately, park officials said there were no incidents to report at Millerton Lake over the 4th of July weekend.

But several incidents have been reported in the last couple of weeks, including two separate incidents where two people were pronounced dead after being pulled out of the water in Millerton Lake — one of them a 15-year-old boy.

More recently, the Merced County Sheriff’s Office said Saturday that a child died while swimming in the Merced River.

“If you don’t know or understand the water, it is one of those unforgiving environments that in literally one second it can completely change the direction of your life because you could lose someone that fast,” said Shane Brown with the Fresno Fire Department.

Brown said the water rescue teams have been busy, adding that it’s important to understand where children are swimming and that they have their life jackets on.

“Test it out, be in the water with them, the flotation device should actually rotate them where their face is up above the water, not rotate them down, so make sure it’s fitted properly,” Brown said.

For Isaac Gutierrez, who was at Millerton Lake on Monday with family, it’s something he’s consistently thinking about.

“I’m a strong believer in that, whenever you’re underwater, always have a life jacket on, even if you’re a strong swimmer, a life jacket can save you,” Gutierrez said. “I make sure my daughter wears one when  out in the water.”

Steve Barber, the supervisor ranger at Millerton Lake State Rec Area, said many people may not realize that there’s not much visibility underwater and there could be cliffs and holes.

“I don’t have a lot of cell service throughout the park, so if you’re going to be swimming, we recommend you do it at a guarded swim where there’s a lifeguard on duty and regardless of your ability,” Barber said.

Many places may not have cellphone service, so Brown said it’s important to have a plan on how to contact for help in case of an emergency.

“How do you call for help is something that a lot of us don’t think about when we go out with our families because we don’t even want to think that way,” Brown said. “But that ounce of prevention, that’s that insurance policy that everyone should have.”