KTRK
Now playing
00:55
3-year-old left in hot day care bus dies
WXYZ
Now playing
01:35
Mom frees baby from hot car, 911 wouldn't help
Seminole County Sheriff's Office
Now playing
01:07
Dashcam shows cop save toddler from hot car
AFP/Getty Images
Now playing
01:12
Your car can be deadly, even when parked
texas hot car death boy trapped child lock pkg _00001207.jpg
KPRC
texas hot car death boy trapped child lock pkg _00001207.jpg
Now playing
01:16
3-year-old boy dies inside hot car in Houston
Mississippi Child dies in car pkg_00001622.jpg
WAPT
Mississippi Child dies in car pkg_00001622.jpg
Now playing
01:15
Mom arrives at day care, gets horrifying news
baby boy dies after left in hot car dnt _00001401.jpg
baby boy dies after left in hot car dnt _00001401.jpg
Now playing
01:18
Police: Baby died after being left in car 9 hours
ac dnt savidge hot car death behavior indicators_00000427.jpg
Harris Family Photo
ac dnt savidge hot car death behavior indicators_00000427.jpg
Now playing
02:11
Timeline of hot car death
exp Mom's fight to end hot car deaths_00002001.jpg
Francesca Trianni for TIME
exp Mom's fight to end hot car deaths_00002001.jpg
Now playing
07:44
Mom's fight to end hot car deaths
Justin Ross Harris, 34, has been charged with murder in the death of his 2-year-old child after he allegedly left the toddler in a hot car for eight hours.
Credit: 	Cobb County Sheriff's Office
Cobb County Sheriff's Office
Justin Ross Harris, 34, has been charged with murder in the death of his 2-year-old child after he allegedly left the toddler in a hot car for eight hours. Credit: Cobb County Sheriff's Office
Now playing
00:54
Justin Ross Harris convicted of murder
Mother reaction baby in hot car body cam pkg_00001318.jpg
Owasso Police Department/KJRH
Mother reaction baby in hot car body cam pkg_00001318.jpg
Now playing
01:24
Mom freaks out after leaving baby in hot car
ctn bts brett and kristie cavaliero daughter hot car death_00003715.jpg
ctn bts brett and kristie cavaliero daughter hot car death_00003715.jpg
Now playing
03:53
Parents describe their hot car nightmare
hot car deaths javaheri orig mg_00003722.jpg
hot car deaths javaheri orig mg_00003722.jpg
Now playing
04:55
Who can stop hot car deaths?
(CNN) —  

A 3-year-old boy was found dead in a bus outside his day care in northwest Houston after he was apparently left inside following a field trip as temperatures outside soared to nearly 100 degrees.

The boy was one of 28 students from the “Discovering Me Academy” who were taken by bus Thursday to a nearby park for a field trip earlier in the day, the Harris County sheriff’s office said.

Houston police said during a Friday press conference that the children were loaded into the van around 10 a.m. and went to Doss Park. The group returned to the day care between 2 and 2:30 p.m.

School records show the 3-year-old had been listed as accounted for on a list of students, the sheriff’s office said. It was only when the boy’s father came to pick him up at 6:30 p.m. that officials discovered the boy was still on the bus.

He was found unresponsive, and the temperature inside the bus was 113 degrees, the sheriff’s office said.

Investigators believe the child was left inside the bus for at least three and a half hours. The boy was transported to the hospital and pronounced dead at 7:45 p.m.

Police are looking into the actions of the two day-care workers and the facility as part of their investigation, police said during Friday’s press conference. CNN has reached out to the academy for comment.

Deputies are interviewing the driver of the bus and a chaperone who was on the field trip, and both are said to be cooperating with the investigation.

“It’s just tragic,” said Constable Alan Rosen.

He also urged parents and caregivers to always look in and around their vehicle before leaving it.

“Do something that always reminds you that you have a loving package in the backseat of that car,” Rosen said.

In the US, hot car deaths are a consistent problem. An average of 37 children die each year from being left in hot cars, according to the safety organization Kids and Cars.

According to NoHeatStroke.org, Texas had the most such deaths from 1998 to 2015, and the month of July is usually the deadliest month.

CNN’s Joe Sutton, Jamiel Lynch, Amir Vera and Sal Sendik contributed to this report.