Dallas police arrested a man who allegedly fatally drowned his two sons on the elder child's first day of kindergarten and then led police on a manhunt.
Naim Mohammed, 32, was caught after a foot pursuit near a neighborhood creek.
Helicopters swarmed the neighborhood, as the SWAT team and dogs were on the ground pursuing Mohammed.
The mother of Mohammed's children, who does not live with him, reported that he forcefully assaulted her and then kidnapped her, along with the two boys, as she was taking them to school at Julia C. Frazier Elementary around 7:15 a.m.
The woman, who police did not name, said she managed to jump out of Mohammed's Toyota Matrix and call police.
Instead of issuing an Amber Alert, a "Critical Missing Persons Report" was filed. Police said the Amber Alert was set for 1 p.m.
"We were trying to follow the trail we had," said Deputy Chief Craig Miller of the Dallas Police Department.
He said police knew early on who they were pursuing.
Mohammed's mother called 911 at 12:40 p.m. after finding her 3-year-old and 5-year-old grandsons unresponsive in her car. She told the dispatcher that "her son had drowned her grandchildren," Dallas Fire Rescue Spokesman Jason Evans told ABCNews.com.
The woman waited with her two grandsons in her vehicle for paramedics to arrive.
Evans said paramedics performed CPR as they rushed the two boys to the Dallas Children's Medical Center, where they were pronounced dead.
"I think everyone is hurt in this case. I think officers who open the back hatch of the vehicle ... it makes each of us think about our own children," said Miller, who added it was unclear whether the car was a hatchback or if the children were placed in the trunk of the vehicle.
Miller said the suspect is cooperating with investigators.
"We are very sorrowful for what took place, and the children and their families who were involved," Miller said.