A man was fatally shot in Houston. Hours later, a boy thought to be his son was found dead in an SUV.

A gunman is wanted in the deaths of a man who was fatally shot Tuesday and a toddler, thought to be the victim’s son, who was found dead in the back seat of an SUV, Houston authorities said.

The unidentified gunman hasn’t been apprehended, Houston Executive Assistant Police Chief Larry Satterwhite told reporters.

Investigators are trying to determine a motive, he said.

The police department released security video Tuesday night that they said showed the gunman.

The boy’s apparent father, 38, was found dead near a strip mall southwest of downtown Houston after authorities responded to a report of a shooting at 1:46 p.m., Satterwhite said.

The victim hasn’t been identified.

Investigators determined that after the gunman and the victim met up, an argument may have followed and the gunman opened fire, shooting the man multiple times and driving away in the victim’s SUV, Satterwhite said.

Five hours later, as authorities were investigating the shooting, a woman called police and reported that her husband and her 2-year-old son were missing, Satterwhite said.

Authorities quickly determined that the missing husband and the shooting victim were the same person, Satterwhite said.

“We didn’t know about the child until she called at 6:36,” he added.

Within 30 minutes, Satterwhite said, officers found the abandoned SUV about a mile away from the original scene. The toddler was in the back seat, unresponsive, he said.

Officers broke the vehicle’s window, began administering CPR and called for an ambulance, Satterwhite said.

“Sadly, it was too late,” he said. “The child had passed in the car.”

The boy’s cause of death was unclear, although Satterwhite said he may have died of heat exhaustion. It wasn’t clear how long the SUV had been left there.

“Pray for this family,” Satterwhite said. “A mother lost her husband, and she lost her 2-year-old child today.”