The Chief Public Prosecutor's Office of Istanbul’s Buyukcekmece district has launched an investigation into Friday's deadly helicopter crash, according to a judicial source.

The office assigned two public prosecutors who will join other crime scene investigators in the probe, the source, who spoke on condition of anonymity due to restrictions on talking to the media, said.

The ill-fated Sikorsky helicopter took off from Istanbul’s Ataturk Airport, east of the city’s Buyukcekmece suburb, Friday and crashed soon after while en route to Bilecik province in northwest Anatolia.

Seven people, including two pilots and four Russian nationals visiting Turkey, were killed, according to a statement by Kugu Aviation, the company which operated the helicopter.

Buyukcekmece is situated on the northwestern side of the city and contains an industrial area and residential neighborhoods. The E5 highway, which runs through the district, was closed after debris landed on the road.