DURHAM, N.C. — Investigators said Monday afternoon that the shooting deaths of four men over the weekend were not random acts and that the motive behind their deaths was probably robbery.

Shortly before 10 p.m. Saturday, authorities discovered four men dead in a townhouse on Alpine Drive in the Durham subdivision of Breckenridge. Police also found two men injured -- a 26-year-old inside the house and the other, 22, who had been shot in the face, outside the house.

Police Chief Steve Chalmers said the victims knew the men responsible for shooting them and that they went to the townhouse with every intention to kill them. While investigators would not release too many details about the case, they did say the shootings were drug-related.

The four who were killed were identified as Lajuan Coleman, 27, Lennis Harris Jr., 24, Jonathan Skinner, 26, and Jamel Halloway, 27.

Police would not release the names of the two men who were injured. They were taken to Duke University Medical Center Saturday. The one found outside was in serious condition Monday, while the other was treated and released, Durham Police Department spokeswoman Kammie Michael said.

The slayings have left neighbors, who describe the neighborhood as usually being quiet and safe, in disbelief. According to police reports, there have been few calls made in that address in the past five years, most of them being false alarms.

Chalmers said Monday that detectives had strong leads in the case. Three men were seen running from the area at the time of the crime.

One was described as a black male with a light complexion, standing 6 feet to 6 feet 2 inches tall and weighing 180 pounds. He was wearing dark jeans and a black and white jacket.

The second man fleeing the scene was described as a stocky black male, standing 5 feet 10 inches tall and weighing 200 pounds. He was wearing a burgundy flight jacket and jeans.

The third man was described as a black male with a medium complexion, standing 5 feet 10 inches tall and weighing 170 pounds. He was wearing a black flight jacket and blue jeans.

Residents said most of the homes on the street are owner-occupied, but the townhouse residents were believed to have rented the unit from an owner who moved to Florida. Neighbors said the property owner told them she performed criminal background checks on prospective tenants before leasing the property.

Kelly Mullins, who lives two doors from the scene, said she heard a few loud thuds through the wall Saturday night, but figured it was someone moving furniture.

Mullins said she'd met at least one of the men living in the house and that they appeared to be young professionals or college students.

A lot of people would visit the house, but Mullins said she never suspected the inhabitants might have been involved in the drug trade.

"We've never had anything like this here," Mullins said. "This is a total aberration. If it can happen here, it can happen anywhere."

Investigators ask for anyone with information about the shootings to contact the Durham Police Department at  (919) 560-4440 or CrimeStoppers at (919) 683-1200.