The Pittsburgh Public Safety Department tweeted that "multiple shots fired in the area of 3700 block of Brighton Road".
The US has suffered at least 458 mass shootings so far this year
The office urged the public to follow safety instructions and avoid the area.
Metropolitan Police Chief Robert Contee told reporters that a 15-year-old was killed while three adults -- two civilians and one police officer -- were wounded but are expected to survive.
The remarks came after the US was shaken by a spate of mass shootings over the past few weeks.
He is scheduled to appear before the court again on July 7.