A surveillance video from a condominium complex in Florida shows an invisible, potentially deadly danger lurking in swimming pools.

The video, shot on April 27 at the Palms West Condominiums in Hialeah, Fla., shows three children shocked while swimming in the condo community's pool.

One young girl in the video instantly goes limp after touching the metal rail in the pool's shallow end. When a man, believed to be the girl's father, goes in to save her, he is also zapped but is eventually able to pull her to safety.

WATCH: Florida Boy Electrocuted While Swimming

In another moment, an adult drops and rolls a child out of the swimming pool, while another girl floats seemingly lifelessly in the water.

That girl, a five-year-old whose muscles were paralyzed by the surge of electricity in the pool, was eventually saved by a man believed to be her grandfather, who rushed into the water to pull her limp body out of the pool.

All three of the children survived the electric shock after they each spending four nights in the hospital.

"I was in the pool and then the metal railing, I was swimming close to it and I felt a shock," Diego Cabrera, 10, the third child who suffered a shock, told local ABC affiliate WPLG.

Inspectors say the shock was a result of an improperly grounded pool pump which malfunctioned and electrified the water. Officials from the condominium complex have declined, so far, to comment on the incident.

Last month, an electrical shock killed a seven-year-old boy in a backyard pool just miles from where this shock occurred.

In the deadly incident, the boy, Calder Sloan, was swimming in his family's pool with a friend when he was knocked unconscious by a powerful shock of electricity. A neighbor performed CPR on Calder while his nanny called 911 but he was not able to be saved.

The medical examiner determined the cause of Calder's death was a faulty pool light.

READ MORE: Pool Light Likely to Blame for Boy's Death, Police Say

Thirteen people have died from electrocutions in swimming pools between 2002 and 2011, according to the most recent figures from the Consumer Product Safety Commission.

Experts recommend looking before you swim to see if any stainless steel surface in the pool is corroded, as that could be a sign of electrical problems.