A toddler died Sunday, the hottest day of 2008, after he was left inside his family's van in northeast Denton County, officials said.
Markus Anthony Lewis, 16 months, died at Children's Medical Center of Dallas, where he was taken by helicopter ambulance from his family's home in the Savannah area, southeast of Aubrey.
The Denton County Sheriff's Office was investigating the incident on Monday, said Tom Reedy, sheriff's spokesman.
Deputies and paramedics received a 911 call at 2:40 p.m. from the boy's family, Reedy said.
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The child had been in the van at least an hour outside the family's home in the 1300 block of Pinehurst. He was unconscious when Aubrey paramedics arrived, Reedy said.
The high temperature at 2 p.m. was 101 in Denton, said Eric Martello, a meteorologist with the National Weather Service in Fort Worth. It eventually reached 105 a few hours later, he added.
Sunday, the weather service confirmed, was the hottest day of 2008.
Reedy said that the boy's family had been at a water park, but they returned a few hours later in two vehicles, including the van.
Each parent apparently thought the other took the child inside after returning home, officials said.
There were no developments Monday in the case, Reedy said.
This article contains information from The Associated Press.