An executive jet crashed in a heavily populated neighborhood of Sao Paulo on Sunday, killing at least seven people and leaving a pile of smoky rubble just months after the city suffered the nation's deadliest air disaster. The plane, a Learjet 35 belonging to a Brazilian air taxi company, slammed into at least two houses shortly after taking off, airport authority Infraero spokeswoman Lucia Ferreira said. Three people injured in the crash - including a child - were hospitalized for treatment, a firefighter identified as Col. Paiol told Record TV. Authorities did not immediately say how many people were aboard the jet, or how many of the dead were in the plane or on the ground. Investigators were trying to determine the cause of the crash, but Ferreira said there were no immediate indications that it was related to a series of Brazilian air traffic chaos and woes including the July 17 crash of a Tam Linhas Aereas SA jetliner, which slammed into a building in Sao Paulo, killing 199 people.