A 22-year-old Manassas Park man was fatally shot at a party Wednesday night in a slaying that appears to be linked to Northern Virginia's most dominant street gang, MS-13, police said yesterday.

Jose Escobar, who worked for a Loudoun County construction company, was shot in the chest in the hallway of a townhouse just outside Manassas, police said.

Maj. Ray Colgan of the Prince William County Police Department said the victim was affiliated with, but not a member of, MS-13 or Mara Salvatrucha, an international gang that has spread from California to Northern Virginia.

Police officials said an acquaintance of Escobar's at the party ran to a neighbor's after the 9:30 p.m. shooting to call for help. By the time police arrived, the only two people in the townhouse were Escobar and the man who knew him, said Detective Dennis Mangan, a police spokesman.

Escobar was flown to Inova Fairfax Hospital and died during surgery, Colgan said.

Prince William Police Chief Charlie T. Deane said he believes the homicide could be solved soon but declined to comment on a possible motive.

"It's early in the investigation, and we're looking at all angles," Deane said. "But we have very promising leads."

One law enforcement source close to the investigation said that in the weeks before the slaying, Fairfax County police "had some information that members of [MS] were upset with" Escobar.

Prince William police said yesterday that Fairfax police, the FBI and members of several gang task forces are assisting in the investigation.

Yesterday afternoon, police were searching the Manassas townhouse in the 8100 block of Community Drive where the shooting happened. The victim's father, Daniel Escobar, 42, and cousin, William Ramirez, who visited the crime scene yesterday afternoon, said they had no idea he was affiliated with any gang.

"He didn't tell me anything about that," said Escobar, who said he worked with his son doing construction jobs and had bought a house with him in Manassas Park last week. "I just feel bad, very sad."

Ramirez said that the father and son got along like brothers and that the younger Escobar "was a nice guy, handsome and a hard worker."

Gang-related violence involving MS-13 has escalated recently in Northern Virginia. The hands of a 16-year-old Fairfax County were mutilated in a machete attack in May by three rival MS members, followed by the fatal shooting of a 17-year-old in Herndon by an assailant sporting an "MS" tattoo on his forehead.

Legislators and law enforcement officials have responded to the increase in violence with harsher laws and an infusion of money and task forces. Police say MS has as many as 1,500 members in Fairfax and possibly 1,000 more elsewhere in the region. Several hundred other youths in the region belong to the18th Street gang and South Side Locos.

Colgan said authorities will soon unveil prevention and intervention methods to deter youths from joining gangs.

Staff writer Maria Glod contributed to this report.

Prince William County crime scene analyst Emily Nusbaum takes fingerprints from the house near Manassas where Jose Escobar, 22, was killed.Ken Werner of the Prince William police collects evidence. Police Chief Charlie T. Deane said,

"We have very promising leads."