On Friday morning in Wilkinsburg, FBI agents, along with assistance from state, local, and federal law enforcement, executed a search warrant, but the overall details of the incident remain unclear. 

According to the FBI, it was related to "specific threats of violence and harm" directed at local law enforcement. 

Sources have told KDKA-TV that they're referring to the shooting last week in Aliquippa when 18-year-old Kendric Curtis Jr. was shot and killed by an ATF agent. 

However, law enforcement said that Curtis Jr. fired first. 

18-year-old shot and killed by ATF agent in Aliquippa

The deadly shooting happened around 6:20 p.m. on Thursday, September 18, and State police said that ATF and FBI agents were working jointly in an investigation.  

18-year-old Curtis Jr. was a student at Aliquippa High School, and hours after the shooting, law enforcement said he was armed. 

He died at Allegheny General Hospital in Pittsburgh a little after 3 a.m. the next morning. 

The Pennsylvania State Police are investigating the shooting. The ATF said in a statement that it is "supporting" the investigation "as needed."

It was not immediately clear why the agencies were in Aliquippa.

"It's a tragedy." Family of 18-year-old killed mourns

At the Linmar Terrace Housing Complex, many were grieving with the loss of 18-year-old Kendric Curtis.

"It's a tragedy," Nicole Luton, Curtis's aunt, said. "It's been a tough few hours, but with God, we're getting through."

Luton and other neighbors said it was wrong to shoot him. 

"I just don't understand, if you had to stop him, why was it that way?" she said. "I mean, every teenager has their ups and downs, but he was able to fix himself. All he wanted to do, and all he kept saying was, I just want to go to school, and I just want to graduate."

Luton and others called him a quiet kid. She says he was always helping out as well.

"He would help an elderly take out the trash," Luton said. "I have an autistic son, and he would spend his time with him, encouraging him."