Miami Gardens police say all four wounded were taken to a hospital Wednesday night.
Capt. Ralph Suarez says about 10 to 12 shots were fired from outside Bunche Park. Authorities are looking for a black Chevy Impala.
A witness tells The Associated Press the injured boy was practicing with a youth football league. The players were all young boys and ran for cover. The witness says the injured men were playing basketball nearby.
No further details were immediately available.