Swimming pool drownings: Know the warning signs

NEW YORK (WPVI) -- It can happen in an instant, and in plain sight: drowning.

It's the swimming pool danger than can claim a life before anyone around even notices.

In a video just posted this week, there are dozens of swimmers in a public

wave pool, and the one in distress is not easy to spot.

In the middle of the screen, a young boy falls off his inner tube and immediately starts struggling. But people around him don't even seem to notice.

Luckily the eagle-eyed lifeguard responds within seconds, saving the boy.

With public pools opening for the season across the country, safety experts are urging parents to stay vigilant for the sometimes subtle signs of drowning, which is the leading cause of accidental death for children under 5.

Some reports estimate that in 10 percent of child drownings, adults nearby have no idea what is happening.

So what should you watch out for?

Signs of distress include the child's head bobbing above the surface, a child who looks like he or she is unable to breathe long enough to call for help, a head tilted back with mouth open and the body vertical.

For more, click on the image above to see the full report from ABC's Reena Ninan.