"According to preliminary information, six people were on board. All of them died," the source said.
He said the helicopter caught fire on impact.
"Currently, the fire is being extinguished," the source added.
The area has been cordoned off.
A TASS correspondent reported from the scene that four bodies have already been retrieved, but the wreckage keeps burning. Firefighters, rescuers and doctors are working at the scene. The crash site is now covered in thick fog.
According to the Russian emergencies ministry, a total of 170 people and over 50 pieces of equipment have been deployed to deal with the aftermath of the accident.
The Russian emergencies ministry’s main directorate in the Khabarovsk region told TASS that the helicopter, owned by a local air carrier, crash-landed at an open site near the streets of Antennaya and Khirurgicheskaya, causing no damage on the ground.
Another emergencies source said the crashed Mi-8 helicopter was on a training flight.
"The Mi-8 was owned by the Vostok company. According to preliminary data, it was on a training flight," the source said.
Vostok top managers could not be immediately reached for a comment.
The Russian Investigative Committee has launched a pre-investigation check into the accident.