Both incorrect, Let me explain:
Firing a semiautomatic weapon is a simple action. You may fire at one person. You may attack once per IP no matter the weapon mode (SA, SS, BF, FA)
Firing a semiautomatic burst is a complex action, that mimics firing a semiautomatic weapon rapidly.
When using a fire weapon action (it doesn't specify it must be a burst) you may use a free action to use 'multiple attacks' therefore splitting your dicepool (after positive/negative/edge modifiers) and attack multiple targets. You can split the pool as many times as 1/2 your combat skill.