Officers had not released any details about the driver of the wrong-way car, a Kia. That person remained hospitalized, police said.
Investigators are looking through evidence to see how fast both cars were traveling and at what point the Kia began heading north in the southbound lanes in the crash between Dryden Road and South Dixie Drive around 8 p.m., Parish said.
Investigators suspect alcohol was involved, Parish said Monday.
“We haven’t confirmed anything. We don’t have any ideas on the speeds yet,” he said.
RELATED: Police: Initial findings don’t point to alcohol in wrong-way crash
Parish said, “We’re still gathering witness statements, analyzing those 911 calls, to find out exactly how this person got on the wrong side of the interstate.
“We don’t know if they crossed over, if they got on an exit, went up the wrong way on the entrance ramp or what. But at some point they crossed over, got into the wrong lanes and struck this family head on,” he added.
Timmy and Tessa Thompson died at the scene, while Karen Thompson died later at a hospital, Parish said. The driver of the Kia was taken by medical helicopter, he said.
“This is horrific,” Parish said. “Not only do we have two adults that were involved. We have a child….who’s lost their life because of this crash. This is absolutely tragic.”
One 911 caller described it as “a bad wreck” while another said “I’m pretty sure no one survived. It is awful.”
A 911 caller near Exit 47 in West Carrollton said “the car left the right hand side going north into the left hand lane and (had) a head-on collision with somebody.”
RELATED: Defying odds: 3 men survive Dayton wrong-way interstate crash
The wreck closed the interstate for nearly four hours, backing traffic up for miles, as staged salt trucks blocked all lanes and forced traffic off I-75, according to the Ohio State Highway Patrol.
Timmy Thompson’s younger brother, Mark Thompson, said all three victims “had big hearts.”
The couple “took care of me when my mom died,” Mark Thompson said. “They were my everything.”
Tessa Thompson, a fourth-grader, was remembered as “a bright light who had a great effect on students and staff” at St. Susanna Parish School, the school said in a statement.
“It is a tragic loss for all who knew her. St. Susanna Parish School and Catholic community expresses heartfelt sympathy and prayers to the Thompson family and their friends affected by this tragedy,” the statement said.
Counselors were on hand Monday morning and will remain available for emotional support, according to the school.
Meanwhile, authorities will be “doing a thorough investigation and pulling some forensic (evidence) on the electronic control modules of the cars in the next day or two to hopefully get an idea of speeds,” Parish said.
Wrong-way fatalities have been an issue on area interstates. Since 2016, more than a dozen people have lost their lives as a result of those types of wrecks.
RELATED: Coroner ID’s family of 3 who died in wrong-way crash on I-75 south in Moraine
In 2017, wrong-way drivers from Huber Heights and Beavercreek died in crashes on I-70 and I-675, the latter which also killed a Miami Twp. teen.
Michael O’Shea, 46, was killed in November after he drove a Ford Explorer east in the westbound lanes on I-70, according to troopers.
Troopers said O’Shea sideswiped another vehicle before hitting a semi-tractor trailer. The truck driver walked away with minor injuries.
A truck driver who said he witnessed the crash reported O’Shea was driving counter to traffic without headlights before hitting a semi.
A month earlier on I-675, Melvin Bonie, 69, of Beavercreek had more than twice the legal limit of alcohol in his blood when his he drove his vehicle northbound into the southbound lanes, authorities said.
The wreck killed himself and Kalip Grimm, a 2017 Miamisburg High School graduate. The accident occurred just north of the interchange of Ohio 48, where police said Bonie entered the highway.
In February 2016, five people - including several local musicians - were killed in a wrong-way crash blamed on alcohol on I-75. The dead included three members of a Dayton rock band CounterFlux and a 61-year-old man who had been arrested for OVI just 48 hours before the crash.
The young victims included four friends: Kyle Canter, 23, of New Carlisle; Earl Miller II, 27, of New Carlisle; Vashti Nicole Brown, 29, of Dayton; and Devin Bachmann, 26, of Huber Heights.
James Pohlabeln, a 61-year-old retiree from Dayton, was the driver of the other car. He had been released from jail just 33 hours earlier in connection with a separate suspected drunken driving crash.
Staff Writer Rick McCrabb contributed to this report.