The incident occurred shortly before 3pm when the single-engine aircraft for unexplained reasons nose-dived to the ground, Vaud cantonal police said in a statement.
Emergency rescue officials found the pilot and a passenger dead at the crash site, near a canal.
Police identified the victims as a 59-year-old man from Geneva and a 48-year-old man from the canton of Vaud.
An initial investigation found that contact with the plane was lost several minutes after takeoff.
The cause of the crash has not been formally established, police said.
The Swiss accident investigation service has launched an inquiry to find out what happened.