A Dorchester woman and a Quincy man were arrested on prostitution charges early Monday morning after police spotted them engaged in risque behavior in a car parked outside 200 Savin Hill Ave.

The Boston Police Department says it has started patrolling the area around Dorchester Avenue and Freeport Street for prostitution and that the couple got snared by that.

According to police, officers on patrol spotted a car stop near a woman walking alone at that intersection around 3 a.m. The driver spoke to her briefly, then she got in the car, police say. Officers followed the car to 200 Savin Hill Ave., where the car stopped and the lights went out. And then, police report:

"At the car, officers observed the two engaged in sexual activity. Both parties were removed from the car and separated so that officers could interview them. Once questioned, officers formed the opinion that the two were engaging in sexual services for a fee. The male suspect stated to officers that he was only giving the female suspect a ride home but could not explain why or how they became involved in sexual activity in the car. The female told officers that they were not engaged in a sex for fee arrangement but instead that the male suspect was her boyfriend whom she had been dating for about seven or eight minutes."

Sarah Feldman, 27, of Dorchester, and Robert Johnson, 41, of Quincy, were both charged with prostitution, sex for a fee, police say, adding two other people were also arrested on those charges earlier.