The plane piloted by a three-man air force crew and carrying 17 civilian passengers was declared missing Thursday evening after leaving Orellana, some 360 miles northeast of Lima, the Defense Ministry said.
An air force spokeswoman told The Associated Press there were "between five and seven survivors." She spoke on condition that she not be identified by name.
She said one of the survivors, a woman, was being taken by helicopter to a hospital.
Julio Barrientos, a government prosecutor in the Ucayali region, where the plane went down, told Radioprogramas, Lima's top radio news station, that rescue helicopters spotted a fire set by the survivors in a jungle clearing. He said there was at least one survivor.
The plane was part of the air force's civic action flights that connect small communities in the jungle not served by commercial airliners.
Officials in Iquitos, the city 625 miles northeast of Lima where the flight originated, said low clouds and heavy rain were hindering rescue operations.
Norman Lewis del Alcazar, vice president of the Loreto region, whose capital is Iquitos, confirmed that the plane was carrying 17 passengers when it left Orellana in a downpour.
Ivan Vasquez, president of the Loreto region, complained that the air force planes that provide the civic action flights are all old.
There are few roads in the vast northeastern jungle of Peru, and other than river travel, which can take days, the flights are the only way to reach distant points.
A TANS Peru airliner carrying 98 people crashed on August 23, 2005 in Pucallpa while making an emergency landing on a jungle highway, killing 31 people. At least 57 people escaped the crash in what one aviation expert Wednesday called "a miracle."