Update Aug. 30: Authorities have found a white van containing the bodies of six family members after their vehicle was caught in floodwaters.

Update 4:50 p.m. Aug. 28: The Harris County Sheriff's Office said on Monday afternoon that it was not immediately able to confirm a report that a family of six was swept away by floodwaters and killed on Sunday.

Houston police Chief Art Acevedo earlier told The Associated Press that he had no information on the reported drowning, but he told the wire service that he is "really worried about how many bodies we're going to find" from Harvey's devastating flooding.

Original report: Family members told a Texas news station that six of their family members drowned Sunday afternoon as they tried to escape from floodwaters brought about by Hurricane Harvey.

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Three members of the unidentified family told KHOU that four children were in a van with their great-grandparents and great-uncle Sunday when it was swept up by the current of flood waters as the van crossed a bridge in Greens Bayou.

The news station reported that the van's driver, the children's great-uncle, was able to escape and cling onto a tree branch. He told the trapped children to escape from the van's back door, but they were not able to, according to KHOU.

The news station said the victims were an 81-year-old woman, her 84-year-old husband, a 16-year-old girl, a 14-year-old boy, an 8-year-old boy and a 6-year-old girl.

Authorities did not immediately verify the report, and no bodies have been recovered.

Houston police Chief Art Acevedo told The Associated Press that he had no information on the reported drowning, but he told the wire service that he is "really worried about how many bodies we're going to find" from Harvey's devastating flooding.

On Monday alone, authorities said they rescued hundreds of people from floodwaters in the Houston area.

Southeast Texas was battered by strong winds and torrential rains starting on Friday, when then-Hurricane Harvey made landfall along the Gulf Coast. It was downgraded to a tropical storm Saturday, but continued to dump rain over the area.