It happened Tuesday evening at an apartment complex on 15928 Old Richmond Rd. near West Bellfort.
The child somehow managed to get out of his parents' apartment undetected, then climbed over the fence and slipped into the water. Cameras around the pool area of the complex show the incident happening.
According to the sheriff's office, the boy remained at the bottom of the pool for a full 15 minutes before his parents found him.
His father went into the water to get him, and tried to give him CPR, but that was unsuccessful.
This is the third child drowning reported in the Houston area in two days. On Monday, a 4-year-old boy with special needs was found face down in a bathtub in northwest Harris County.
According to the sheriff's office, the 27-year-old mother was bathing her 4-year-old and 1-year-old boys when she walked away. It's not clear how long she was gone.
When she returned, she found the 4-year-old face down.
READ MORE: 4-year-old boy with special needs dies after being found face down in bathtub
Then, in a separate incident on Monday, deputies in northeast Harris County responded to a deadly drowning incident involving a child.
According to officials in that case, a boy, who was also 4 years old, wandered away from the apartment area and ended up near the pool.
Officials in both Harris and Fort Bend County are urging parents to teach their kids water safety and how to swim.
"Every year, we seem to come and talk about this, about how are we going to keep children from becoming victims to drown. And I don't know if it's just more awareness, if it's education, it's paying more attention. I don't know, but it's just, we don't want to see anymore," said Sheriff Troy Nehls.
Last year, ABC13's Jeff Ehling met volunteers with a local non-profit called the Judah Brown Project, which is aimed at providing water safety information and drowning prevention after the founder's son drowned in 2016.
The group says the number of child drownings this year is not normal, and that the stay-at-home orders are leading to a dramatic increase in child drownings. There have been more than 16 child drownings in Texas so far this year.
WATCH: Three pool safety tips parents should know
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