Neighbours described the event as “horrible irony”.
According to police, Mr Merriett was attacked after he left a property in which he was filming to pick up more equipment from the van.
He was shot multiple times before being taken to the hospital, where he was pronounced dead.
Philadelphia Police Chief Inspector Scott Small said in a statement: “They were inside a private residence. They were interviewing and filming some family members whose children were victims of gun violence in the last two to three years.”
Police are still trying to piece together what happened. All the filming equipment was left on the pavement when authorities got to the crime scene.
“We don’t know if it was a robbery (or) if his wallet and money were taken,” Small added.