Jakarta, Indonesia (CNN) -- Indonesian authorities said Wednesday that they had found part of the flight recorder of the Russian passenger jet that crashed into the side of a volcano during a demonstration flight last week, killing 45 people.
Searchers retrieved the cockpit voice recorder, which records communication between pilots and air traffic controllers, but have so far been unable to locate the flight data recorder, said Vice Marshal Daryatmo, head of the National Search and Rescue Agency.
He said the voice recorder would be brought to Jakarta for analysis.
Rescue workers found no surivors from the Sukhoi Superjet 100, Russia's newest passenger plane, which slammed into Mount Salak after disappearing from radar screens on May 9.
Most of the wreckage of the plane is on a steep slope at an altitude of 6,000 feet, making it difficult to reach.
The Indonesian and Russian authorities are investigating the cause of the crash, which remains unclear.
The plane was on a demonstration flight for Indonesian Ministry of Transportation officials and representatives of Indonesian airlines.
It was the first crash of a Sukhoi Superjet 100, according to the Russian state-run news agency RIA Novosti.
The plane was on its second demonstration flight of the day when it lost contact with air controllers at Jakarta's Halim Perdanakusuma Airport.
The Sukhoi jet arrived in Jakarta as part of a demonstration tour of six Asian countries. It had been to Myanmar, Pakistan and Kazakhstan, and was scheduled to visit Laos and Vietnam after Indonesia, RIA Novosti said.
Sukhoi manufactures military aircraft and is known especially for its fighter jets. Its civilian aircraft is narrow-bodied with a dual-class cabin that can transport 100 passengers over regional routes.