EMBED >More News Videos Investigation continues into quadruple killing in Southwest Philadelphia. Watch the report from Bob Brooks on Action News at 4:30 p.m. on Nov. 20, 2018.

EMBED >More News Videos Commissioner Ross holds press conference on quadruple murder in Southwest Philadelphia.

EMBED >More News Videos 4 shot execution style inside SW Philadelphia home. Watch the report from Sarah Bloomquist on Action News at 4 p.m. on Nov. 19, 2018.

Just saw bodies of 4 young people, who were executed in a rowhouse on 5100 Malcolm St. It is the worst crime scene I have seen in my 20 years w/ the PPD. It is going to take everyone in this city to reduce this senseless violence. My thoughts and prayers are with their families. — Derrick Wood (@PPDDerrickWood) November 19, 2018

SOUTHWEST PHILADELPHIA (WPVI) -- Crime scene investigators returned to Malcolm Street Tuesday morning in Southwest Philadelphia where a gruesome discovery was made a day earlier.Four people were found executed inside of a home. Two men and two women were each shot once in the head. Police confirm the two male victims were cousins.Investigators were seen bringing evidence bags out of the house and fingerprinting the front door.At all times, an officer has remained outside the home since the bodies were discovered around 12 p.m. Monday.Greg Brinkley had to come and see things for his own eyes. He wanted to see the police and crime scene investigators for himself before he could believe that his great nephew was killed here."You know, I'm in shock. I haven't seen the rest of my family yet," Brinkley said.He says his great nephew is one of the four victims found executed inside the home.Right now no motive or suspects have been declared or named by police. But Brinkley says someone knows something."I know this about the streets. Four people don't get killed and nobody knows about it, I'm telling you. Somebody know and we going to find out," he said.So far, police haven't release the names of the victims. But they said one of the men is 31-years-old, the other is 28.One of the women is 20-years-old and the second female's age hasn't been released.In a Tuesday morning press conference, Philadelphia Police Commissioner Richard Ross said this was not random."I don't think this was random. I don't think anybody was burglarizing a home or anything like that. That's just being very honest," Ross said. "We don't have a lot to go on. And that's being very blunt about it, so hopefully someone will hear something."Police said the victims were found dead in the basement after a relative called in for a welfare check."All four of these individuals were executed. There are no ifs, ands or buts about it," Ross said on Monday.Ross says the home appears to be in the process of being renovated. In fact, Ross says a neighbor heard bangs Sunday night, which he assumed had to do with ongoing work at the house.There were no signs of a struggle, which leads investigators to believe the victims may have been led down to the basement."The house is not in disarray. It doesn't look like there was a struggle upstairs. Just looks like they were either taken down there or they were already down there for some reason and they were shot. It doesn't appear to be a struggle," Ross said.The neighborhood is rapidly gentrifying and the block is considered safe. This level of violence stunned neighbors and even the commissioner who went to see the crime scene for himself."I can't get my mind around the fact that you have people walking around capable of such vicious acts," Ross said.Shortly after the discovery was made, Philadelphia Police Captain Derrick Wood released a tweet that partly read, "It is the worst crime scene I have seen in my 20 years with the Philadelphia Police Department."While the investigation continues Brinkley says what's happened has blindsided his family."Our family is devastated, because he couldn't hurt a fly and we know that," Brinkley said. "But if he was into something that deep, we didn't know about it."If you have any information, you are urged to contact police.-----