Ellen Goldberg, NBCDFW.com
Relatives of two children allegedly drowned by their father say they never expected him to hurt his children.
A man accused of drowning his two children on the first day of school faces capital murder charges.
The bodies of the boys, ages 3 and 5, were found in Naim Rasool Muhammad's car at East Ledbetter and Singing Hills drives.
At 12:40 p.m., a 911 caller said her son had drowned her grandchildren. The caller told the fire department she had the children with her and was waiting for paramedics, according to officials.
Paramedics arrived and transported the children to Children's Medical Center in Dallas, where they were pronounced dead.
Deputy Chief Craig Miller said Monday afternoon that investigators believe the children, 3-year-old Elijah Mohammed, and 5-year-old Naim Mohammed, were drowned. The children were found in the back of a silver station wagon that belongs to their father.
Investigators are trying to determine where the children were killed.
Naim Muhammad, 32, was detained after a foot pursuit and struggle with police in the 6500 block of Lazy River Drive, a few blocks from where his car was found. He was taken into custody in a creek bed near his home.
Police identified the children as Elijah and Naim Mohammed, but the father's name is listed as Muhammad in court and jail records.
Mother Tried to Get Help From Constable
Police said Monday afternoon that Muhammad abducted the children and their mother while she was walking them to school at about 7:15 a.m.
A police report said he forced the children and their mother into his vehicle by threatening her with a brick. They were walking from their home on Terrell Street in South Dallas to Frazier Elementary School a few blocks away.
Police said the woman and her children were not at a school when they were taken.
The mother jumped out of the car in the 100 block of Camp Wisdom Road when she saw a Dallas constable drive up to get help. The mother told police Muhammad jumped the curb and drove off when she got out of the car.
The constable called Dallas police but did not chase Muhammad. She only served court papers, did not have red lights or a siren and is trained not to chase anyone.
Police Say There Was History of Domestic Violence
Miller said there was a "continuing family violence situation" between Muhammad and the boys' mother.
The mother told police Muhammad had made threats against her and their children. She and Muhammad have three children, police said.
Muhammad was arrested in February on suspicion of punching the children's mother. According to the police report, Muhammad grabbed their then 4-year-old son and left with him.
"I knew he was troubled, but I didn't expect him to hurt his own kids," said Gabrielle Armstead, the children's aunt.
"He did yell a lot and use the kids as a target, so he took the thing that was closest to her, and that was her boys," she said.
The children's mother and Muhammad had recently separated. The mother and the children were living with her parents in Southeast Dallas.
Witnesses said Muhammad tried to break into their home later in the morning. A shattered window could be seen at the house.
The couple's 1-year-old son was not home at the time.
Relatives said the family got together on Saturday for a cookout to celebrate the children going to school. Muhammad and the children's mother got into an argument, and he was asked to leave, the family said.
"We [were] hoping for them to start school today and be with the rest of the kids and enjoy life, but someone ended their life shortly," Armstead said.
Police said they are working with Child Protective Services to determine if there was a history of abuse.
The 1-year-old child is in the care of Child Protective Services. Relatives said the children's mother feels as if she has lost all of her children.
Police Had Planned to Issue Amber Alert
Dallas police said the children's bodies were found before they could issue the Amber Alert they were planning on announcing at 1 p.m.
Miller said Monday afternoon that officers knew they were looking for the children's father. Officers were following every lead and did not have enough information to justify an Amber Alert, police said.
Investigators said there was no legal reason the father could not have his children and were working to confirm that he made threats to the mother and the children before the children's bodies were found.
Muhammad's photo, left, was taken in February of this year. In September 2009, he pleaded guilty to aggravated assault with a deadly weapon, a second degree felony, and received five years' probation. According to court records, the charge stemmed from a complaint from his sister that he had struck her in the head with a hammer.
He also has prior convictions for possession of marijuana, burglary of a vehicle and theft by check.
Muhammad has been charged with two counts of capital murder.
He was booked into Dallas County Jail at 6:51 p.m., where he is being held on $2 million bail. Miller said Monday afternoon that Muhammad was cooperating with the investigation.
NBC 5's Ellen Goldberg and Scott Gordon and The Associated Press' Jamie Stengle contributed to this report.