(CNN) -- Indigenous Indians located nine survivors of a plane that crashed in a river in the Amazon rain forest with 11 people onboard, according to the Brazilian air force.

The nine passengers were in good health, the air force said Friday.

Of the two people missing -- a passenger and a crew member -- one is believed to be dead. The air force did not provide further details.

The plane was on its way to deliver health supplies Thursday when it crashed. It had taken off from Cruzeiro do Sul in Acre state and was headed to Tabatinga in Amazonas state.

The plane landed in the Itui River between the tribe settlements of Aurelio and Rio Novo. Indians of the Matis tribe, who live in Aurelio, initially located the plane and alerted the Brazilian air force, which sent search planes to the site.

Before the passengers were located, at least eight aircraft had been dispatched for the search operation, the air force said.

Members of the Matis, an indigenous tribe of about 300, live deep in the rain forest.

Other area tribes were helping in a search for the two missing passengers along the shores of the Itui.