According to the Rich County Sheriff's Office, the shooting happened at Sweetwater Trailer Park around 1:50 p.m.
The suspect fired shots into homes at the trailer park, then drove into a house and shot a husband and wife with a shotgun, a representative for the Sheriff's Office said.
The husband was shot in the abdomen and his wife was shot in the upper left chest and arm. Both were taken by ambulance to a hospital for treatment.
Kelsen Jones, who lives a few houses away from the couple, spoke with FOX 13 about them.
"They're always very nice, inviting us down to the local, you know, every weekend they'll do like a barbecue throughout the trailer park," Jones said. "[I'm] absolutely shocked. You know, Garden City's a very small town and you don't hear about stuff like this happening."
The suspect was pronounced dead at the scene. Sheriff's Office officials said he was found with a shotgun in his car, but it's unclear if he killed himself.
"The deputy actually removed that [shotgun] from the car. When he walked up on the car, it was sticking out the car window," said Rich County Sheriff Dale Stacey.
The names of the people involved have not been released.