They were all members of the violent gang Mara Salvatrucha, and they quickly spread out through the Prince William County townhouse. They were about to take out one of their own.

One went here, one went there, until all the exits were blocked. An argument began, and then -- bang -- Jose "Snoop" Escobar, 22, collapsed on the floor, a bullet wound in his chest. Three more shots were fired at Escobar's uncle, missing him, before the car with the loud muffler raced away from Community Drive.

Prince William police said the car and a bloody shoe print found near Escobar's body belonged to Wilfredo "Nino" Montoya-Baires, 25, a Reston area construction worker, according to court records filed in Circuit Court. Montoya-Baires and Reynaldo Alexander Cordova, 21, of Falls Church were arrested last week and charged with first-degree murder.

The owner of the home, Carlos Avalos, has been charged with murder in a warrant but has not yet been arrested, said Sgt. Kim Chinn, a police spokeswoman. The victim's uncle, Raul "Cross" Escobar, was not injured in the shooting. Raul Escobar, a known MS-13 member, was charged with obstruction of justice because he "lied to investigators about what happened" that night, she said.

The allegations in last week's gang-related slaying, spelled out in detail in court records, provide a chilling recitation of how Northern Virginia's most dominant and violent gang allegedly exterminated one of its own. The slaying is the 10th Hispanic gang-related homicide in Northern Virginia in four years and is being investigated by several law enforcement agencies, including the FBI.

Police have not said why Jose Escobar was the victim of an apparent hit inside what they called a known MS-13 gang house. According to the court papers, Montoya-Baires was the triggerman, shooting Escobar with a 9mm firearm and then firing three times at his uncle. Cordova allegedly blocked the front door so the victim could not run, the records said.

"Any time you've got gang members participating in murders, probably the violence is going to escalate," Prince William County Commonwealth's Attorney Paul B. Ebert said yesterday. "This attack causes us great concern."

After the house in the 8100 block of Community Drive emptied out, a neighbor heard a car with a loud muffler speed away. The uncle went to a neighbor's to call 911, and Escobar's body was flown by helicopter to Inova Fairfax Hospital.

Montoya-Baires told police he was home the night of the shooting from 5:30 to 11:30. His girlfriend and father, who live with him in a Fairfax apartment, disputed his alibi.

Not only that, police said, but a shoe belonging to Montoya-Baires "matched in size, shape and tread pattern" the bloody shoe print found near Escobar's body.

The girlfriend told police that "Nino" was driving a 1992 light-blue Honda that is "equipped with a muffler that is loud and similar in sound to the vehicle that was heard leaving the scene of the crime," according to the search warrant affidavit.

Police searched the house, which is owned by Avalos, according to court records, and recovered an array of items: a bag of marijuana, a bag of 9mm Luger bullets, a knife, stereo speakers and a kitchen table marked with graffiti, four shell casings and one round.

Gang members gather at the two-story brick townhouse to "hold meetings and engage in criminal activity," the search warrant affidavit said. Police are searching for the home's owner, Avalos, to obtain DNA evidence from him to compare with evidence from the scene.

Prince William and Fairfax County gang investigators found Montoya-Baires at an apartment complex in the Seven Corners area, and he agreed to be interviewed at the Manassas police station before he was arrested, court papers said. Montoya-Baires and Cordova face a Sept. 21 hearing in Prince William County Circuit Court.

Both sport "MS" markings, according to court papers. Montoya-Baires has one on his stomach; Cordova has a tattoo etched into his back. Northern Virginia has as many as 2,500 members of MS-13, according to police. In Prince William, they have been involved in numerous crimes: murder, recruitment of a juvenile for a criminal street gang and grand larceny.