Brazilian authorities say a helicopter has crashed into a house in Sao Paulo, killing the pilot and injuring the three passengers, but not hurting anyone on the ground.

It's not clear what caused the Monday crash.

A light rain was falling over most of Sao Paulo during the crash, but there were no reports of heavy downpours typical during the South American summer.

A spokesman for Brazil's air force says the aircraft that crashed was a Bell 206 helicopter that can carry up to seven passengers and a pilot.

It was being operated by as an air taxi. Sao Paulo has one of the world's largest private fleets of helicopters, used as a means of bypassing extremely congested roads.