It has been confirmed by L that if a person's name is written in the Death Note, and they are written to die in a form that specifies another person's name, (like "L Lawliet will die after he deletes all his evidence on Light Yagi and goes to Misa Amani's apartment") then all of them would die of a heart attack.
This is due to Rule XI
- [...] once the victim's name has been written, the individual's death can never be avoided.
The rule above may appear to trump Rule X
- Whether the cause of the individual's death is either a suicide or accident, if the death leads to the death of more than the intended, the person will simply die of a heart attack. [...]
However, it does not. "The victim" is automatically anyone whose name is written in the Death Note.
Suppose somebody uses a Death Note to kill someone and specifies another person's name in the description. Will that person — who is specified, but not intended to be killed — live, if the Death Note user does not know their face?