Kin: Tossed Kids' Mom Mentally Ill

Authorities have recovered the body of a child in San Francisco Bay believed to be one of three youngsters tossed into the water, allegedly by their mother.

A woman who says she is the mother's cousin told authorities the mother is unstable, reports CBS News correspondent John Blackstone.

He says dusk was falling when firefighters, police and the Coast Guard began a desperate search.

Witnesses on a pedestrian pier reported seeing a woman strip three young children naked, then throw them into the bay. The witnesses saw an abandoned stroller and a pile of children's clothing on the pier.

"Fire Department and Police Department crews were on scene within four minutes to attempt rescue efforts," says San Francisco Fire Chief Joanne Hayes-White.

Flares were used to light up the water as the search stretched into the night.

The first body was found more than three miles from the pier, near a yacht club not far from the Golden Gate Bridge.

And, authorities say, the cold water and powerful tides made it unlikely the other two could survive.

A woman on the pier, believed to be their mother, was taken into custody, Blackstone says.

"They detained an individual who has now been taken into one of our facilities," says San Francisco Police Chief Heather Fong. "Because of the nature of the injuries, the possible fatalities at this time, this case is now assigned to our homicide unit."

The San Francisco Chronicle reports in its Thursday editions that the mother, Lashaun Harris, 23, of Oakland, was charged with three counts of murder. Her children were identified as Trayshaun Harris, 6, Travante Greely, 3, and Joshua Harris, 1, the Chronicle says.

As the search for bodies continued, Asia Powell, who identified herself as a family member, arrived at the pier with a photo of three children, Blackstone reports.

Their mother, her cousin, she said, is struggling with mental problems.

"When the doctors seen her, she would straighten up, you know," Powell said. "And then, when she wasn't around the doctors, she would be on a whole different level … off her medication."

The Chronicle says Lashaun Harris told authorities voices had told her to throw her children into the water.