A 74-year-old Woodbridge woman was raped by a teenager Saturday night after she answered a knock at her front door, Prince William County police said.

The woman immediately called police from her home to report that she had been robbed and raped by a stranger. Police said an officer stopped a suspect minutes later, blocks away from the woman's home, carrying one of her credit cards.

Prince William police identified the suspect as Marcus Tyree Stanton, 18, of Armstead Court in Woodbridge. He is being held without bond on charges of rape and burglary with intent to commit rape, police said.

Police spokesman Dennis Mangan said yesterday that the victim opened the door for Stanton after he knocked about 9:45 p.m. Saturday. Mangan said the victim reported that it was "very dark" at the front of her home when she opened the door. He said the victim was home alone at the time.

"She opened the door. He pushed her through the doorway, sexually assaulted her and took some property," Mangan said.

Police said the victim did not recognize Stanton, whose family lives a few blocks away in the Marumsco Village neighborhood just east of Interstate 95.

Officer James Nunnallee spotted Stanton at Armstead Street and Hylton Avenue and stopped him, police said.

The rape was the county's first serious violent crime of the year, police said. Mangan said such "stranger rapes" are quite unusual in Prince William. Of the 84 rapes recorded in the county in 1998, 74 involved suspects who knew the victim. About 25 percent of 1998 rapes in the county involved adult victims.

"This is not common, especially with a victim of this age," Mangan said. "We don't have stranger rapes that often, let alone something like this."