The accounts of the baptism of Jesus are found in Matthew 3:13-17, John 1:29-34 and Luke 3:21-22.
The only individuals we know for sure who attended Jesus’ baptism was Jesus himself and John the Baptist. It is likely, however, that there were many other unnamed individuals who were present (See Luke 3:21). The account says that many others were baptized just prior to Jesus’ own baptism. It is reasonable to assume that many of these witnessed Jesus’ baptism and, along with John, may have also heard the voice from heaven and saw the dove descend upon Jesus.