Death: Heart Attack (1.1)
Killed by: Kira
Reason: Light randomly wrote his name in to test out the Death Note. He killed and wounded six people in Shinjuku the day before Light wrote his name. He was currently barricaded in a nursery school with infants and daycare workers.

Death: Car Accident (1.1)
Killed by: Kira
Reason: Light was testing out the notebook for the first time. This guy was bothering a girl, and so he wrote down his death. He died when a truck hit his motorcycle.

Death: Heart Attack (1.2)
Killed by: Kira
Reason: He claimed to be L on the news, and Light killed him for this. Of course, L did this just to check if Kira could really kill by being far away. The guy though was an imprisoned criminal.

Death: All of them died of heart failure, but also did many different things. Shirami was inside a jail when he cut his own fingers and with his blood drew a star with a circle around it on the wall. Yadanaka left a strange note before dying, reading (direct Japanese translation) “With fear I know it/ Only from living in vain in this / nerve-recking state that I/ know this./ Ultimately, he who calls/ out to me, he who/ yearns for my death, will kill me./ Of course I knew it./Definitely for Kira I am just…/Literally a prey.” In the American version it says: “Lord Have Mercy/ Do what I can, I’ll either be hanged or/ you know it, killed by Kira, I/ know about him, he’s going to get me.” Osabuyoshi escaped prison and entered the restroom to die at 6pm. Literally a prey. Matsuhshiro died by blood loss when he entered a convinient store with a knife and stabbed himself in the stomach at 1:30am. (1.6)
Killed by: Kira
Reason: These people were killed so that Light could test out how much he could control people before their deaths. L figured this out. But basically, I grouped them together since they were under the same basic experience.

Death: He hijacks the bus with Ray Penber. Light convinced Penber to show him his ID. Kiichiro is then handed a note by Light, which is a piece of the Death Note. For this reason, he is able to see Ryuuk and shoots at him, with no avail. Scared, he then runs out of the bus only to be run over by a car. (1.7)
Killed By: Kira
Reason: Light organized it so that he could convince Penber to show him his ID. This way he could get rid of him. He used Kiichiro to do this.