SAN DIEGO (KABC) -- A pregnant woman and her young son seen begging for money in a San Diego shopping center parking lot were caught driving off in a Mercedes-Benz.Melissa Smith told sister station KGTV she saw the panhandler and her son at Eastlake Village Center every weekend for two months. The woman's boyfriend would join them on the weekend, she said."I felt bad. There's a pregnant lady with a little boy who is down on her luck," Smith said.The woman would hold a cardboard sign that said "please help," and plenty of people did."Lots of people gave them money. Probably five people in five minutes gave them money," Smith said.Smith said she was getting gas when she saw the couple at the usual spot."They were leaving and I noticed they went into a Mercedes Benz. I thought, 'Wow, a Mercedes Benz?'" said Smith, who noted the car appeared to be new.Smith shook her head and got in her car to drive away."Lo and behold, they were in front of us. Here they are counting money, laughing. Their little boy is not in a car seat or a seat belt. He's all the way in the front seat with them," Smith said.Smith watched them drive to a McDonald's at another plaza on Bonita Road."She sits there with the sign. He goes (and) parks the Mercedes. They put up the sign and not less than five minutes, here she is getting money from all these people," Smith said.Smith took pictures of the woman and boy at the new location. The woman spotted her, got angry and started yelling, Smith said."Next thing I know, she picked up this big boulder," Smith said, "I don't know if pregnant people can do that, but it was pretty big over her head and coming at me with this rock."Another witness saw the entire incident and called 911."She grabs her little boy and takes off through the middle of the parking lot," Smith said.A Chula Vista Police Department spokesman told KGTV that the couple had left before they arrived. Smith gave police the license plate number to the Mercedez-Benz.That license plate number led to an Encinitas apartment complex called Encinitas Heights Apartments. Residents said rent is $2,500 a month.The resident of the Encinitas home responded to KGTV's requests for comment, but said she had just moved in. The couple living there before had recently picked up and left.Smith said she wants people to know about this couple before they find a new place to panhandle with whom she believes to be their son."I feel bad. Don't give these people money. They don't need it. They're driving a Benz," Smith said.