Yellow police tape blocked off the 4400 block of East Yates Road Thursday night where the incident happened.
Police say at about 2:45 p.m. they received a 911 call for a possible drowning at a home with an indoor pool.
When they arrived, they found a teenager attempting to resuscitate her 20-month-old brother.
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"[The sister is] certified CPR, found the baby who was in the pool and attempted to resuscitate the baby," Bensalem Police Sergeant Andrew Aninsman said.
The child was rushed to Aria Hospital Torresdale Division where he later died.
Police say family members had been in the indoor pool earlier with the child and then retired to the nearby living room with the child.
"And they then realized the baby was...they couldn't account for the baby, and they went into panic mode looked around and eventually found the baby in the pool," Aninsman said. "Our investigation, so far, it appears to be a very horrific, tragic accident."
Authorities say the drowning serves as a heartbreaking reminder of how water can be a silent killer.
Sadly, the Red Cross and the U.S. Consumer Product Safety Commission says since the Memorial Day weekend and before today's incident, Pennsylvania ranked fourth, behind Texas, Florida and Arizona, in the number of child drownings or near-drownings.
With today's incident, it appears Pennsylvania may now rank third.
"That's disturbing. There's no particular reason why Pennsylvania is that high on the list necessarily, but it is distressing to know," Dave Schrader of the Red Cross said.
One of the things the Red Cross is trying to emphasize this holiday weekend is being safe around pools. Interestingly, most child drownings do not occur on beaches or lakes, but in residential swimming pools.
"Couple things we stress, number one, have a fence around your pool. It's very difficult to get in and out of, hgh enough that kids can't just climb over it. That's first and foremost," Schrader said.
They also say to have a child-proof gate at the pool and consider putting an alarm on it, as well.
Most of all, the Red Cross and police stress this time of year, it's important that everybody is extra vigilant about safety when taking part in water activities.