Police say the three people -- an 8-year-old girl, her 32-year-old mother and her 62-year-old grandfather -- drowned.
The call came to the police department from a neighbor who heard screaming in the backyard. She thought someone had fallen, but when police got to the house, all three people were dead in the pool.
Authorities called an electrical contractor to the home and sources say they believe there may have been an electrical issue in or near the pool that led to the deaths.
Police have not confirmed that theory.
"This is a devastating day for our entire community. It is too early to determine exactly what happened. We are working with the Middlesex County Prosecutors office and will release information as it develops," East Brunswick Police Chief Frank Losacco said.
Other family members were said to be inside at the time of the incident.
The family had just moved in last May but were said to be friendly and outgoing.
Few other details were released but the investigation is ongoing.
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