NEW YORK (AP) An 8-month-old baby was nearly snatched by a stranger on a Manhattan street while being pushed in his stroller, police said, but a bystander intervened to foil the abduction attempt.

A 46-year-old woman was in custody and undergoing psychiatric evaluation Saturday. She hadn't been charged, at least as yet.

A nanny was pushing the stroller when a stranger walked up and tried to grab it from her Thursday afternoon in the Chelsea neighborhood, police said.

"She was saying, 'You're a liar! These are my babies!'" said UPS driver William Marte, who was nearby. He noticed the struggle and stepped in to help.

"I told the lady, 'Let it go just keep going,'" and she did, he told reporters.

She was gone when police arrived. They found the suspect after putting up fliers with a sketch.

Yancy Matson, who works nearby, told WABC-TV that he'd seen the woman in the area a number of times.

Marte, 51, said he "did what came from my heart."

"I've got two kids. I did what I was supposed to do," he added.