Two women suspected of operating a brothel out of their Prince William apartment were arrested this week after police learned that dozens of men were frequenting their Gambril Drive home and allegedly paying for sex.

Several reports from concerned residents prompted the investigation into activity at an apartment in the Tanglewood complex, just outside Manassas, where scores of men were seen entering and leaving after brief visits. Police also arrested two men on charges of frequenting a house of prostitution.

"People were looking at this place and seeing people coming and going, and coming and going," said Prince William County police spokesman Dennis Mangan. "They were concerned about questionable activities."

After searching the apartment Tuesday, county police arrested Liz Caro-Rodriquez, 22, of Georgia, and Marlene Vazquez, 23, of the Bronx, N.Y. Both women were charged with prostitution and were released on $2,500 bond.

Two men, Juan Baten-Cuyuch, 25, of Chantilly, and Jose Ramirez, 30, of Lake Ridge, were charged with frequenting a house of prostitution. Both men were released on $1,500 bond.

Police began the investigation after a nearby resident reported that she had seen several men frequenting her neighbor's apartment and that she suspected they were buying drugs or paying for sex. According to a search warrant filed in Prince William County Circuit Court, at one point the resident witnessed 11 cars arrive at the apartment in a one-hour period.

The resident also told police that several men had gone to her apartment mistaking it for the one other men had been frequenting. "One male that came to her door told her that he was told if he gave her $50, she would give him sex," according to the warrant.

Police conducted surveillance at the apartment in the last two weeks and noticed a total of 23 men entering the apartment in a 33-minute period, most of them staying for a short time, according to the warrant. Two men who worked for the apartment's construction contractor told police that they went to the apartment, asked if they could enter and were told that the apartment "closed" at 10 p.m. and that "they were welcome to come back after 4 p.m. the next day," according to the warrant.

"The person that answered the door explained that on the weekends they stop business at 10 p.m. so they can party," according to the warrant.

Tuesday's arrests mark the second prostitution ring county police have broken up in the last year and a half, police said. Mangan said prostitution is not a major problem in the county.

In May 1998, Prince William County police detectives went undercover in an attempt to flush out a prostitution operation at the Tropicanna Tanning salon on Sudley Road, where three women were allegedly offering sex to men after their regular massages. During a sting there, police witnessed a woman placing a condom on a client in one of the salon's 12 private rooms and other women allegedly offering sex.

Two of the women arrested pleaded guilty to disorderly conduct.