DALLAS (AP) - When two Harris County Sheriff's deputies found him clinging to a tree branch, water up to his neck, Samuel Saldivar was distraught and in tears, describing how he watched a van carrying his elderly parents and his brother's grandchildren sink into Greens Bayou, a relative said.

Saldivar's sister-in-law, Virginia, told The Associated Press Tuesday that the same deputies came to the suburban Houston home where she and her husband have stayed since volunteers evacuated them Monday for information about the children, aged 6 to 16, and her in-laws.

"They wanted to make sure that we understood how they found Sammy," she said.

After his parents' northeast Houston home began to flood early Sunday, Samuel Saldivar borrowed his brother's van and drove to pick up the relatives. He told deputies that while crossing a bridge, a strong current lifted the van and pitched it forward into a drainage channel.

Saldivar climbed out of the driver-side window but the van's sliding door was partially submerged and would not open, Virginia Saldivar said. He yelled at the children to try to escape out the back, but they were unable. Virginia Saldivar said her brother-in-law could only watch as the van disappeared underwater.

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This 2014 photo provided by Virginia Saldivar shows her grandchildren Daisy, from left, Xavier and Dominic Saldivar, three of the four children presumed dead after their van sank into Greens Bayou on Houston's eastside. Virginia Saldivar says she presumes six members of a family, including four of her grandchildren, have died after their van was carried by a strong current into the bayou and sank. (Virginia Saldivar via AP)

Hurricane Harvey

Saldivar believes her husband's parents, Manuel Saldivar, 84, and Belia Saldivar, 81, drowned along with her grandchildren: Daisy, Xavier, Dominic and Devy.

The Harris County Sheriff's Office could not confirm the deaths because no bodies had been recovered, Deputy Thomas Gilliland said.

"The water levels are so high, we can't find anything," he said.

Virginia Saldivar said she lives in the same neighborhood as her relatives, but she and her husband left during a calm spell Saturday to watch the boxing match between Floyd Mayweather and Conor McGregor. The children's mother had left the four at home, she said. The widespread flooding prevented them from getting home until Sunday afternoon.

Virginia and her husband fled their home Monday evening when water rose to about 8 feet (2.44 meters) outside their front door. Volunteers helped get the couple to dry land.

Twice since Sunday, the children's mother went to the site where Samuel Saldivar told deputies the van disappeared, but the Coast Guard wouldn't let people through, Saldivar said. The children's father, her son, who she said is in prison for violating parole, first heard about the incident Tuesday. She told him during an allotted 10-minute phone call.

As soon as it is safe to return to Houston, Saldivar said, she and her family will go looking for the bodies themselves. She said the sheriff's deputies told her the strength and direction of the current meant that the van could have been carried as far as the Port of Houston, about 8 miles (12.87 kilometers) southwest.

"The hope is that we find the bodies," she said. "It's the last thing I can do for them."