A 17-year-old Helena resident has been charged with killing one teenager and injuring two others in a shooting that apparently stemmed from an argument over a girl. Sebastian Walter Olivares-Coster made an initial appearance before District Judge Jeffrey Sherlock Thursday morning on one count of deliberate homicide and two counts of attempted deliberate homicide. Bail was set at $500,000 and Olivares-Coster was taken to the youth detention facility in Great Falls. Olivares-Coster is charged with killing Cory Adam Andrewski, 16, and shooting two others. "This is one of the most brutal homicide scenarios imaginable," Lewis and Clark County Attorney Leo Gallagher told Sherlock. "In coldblooded fashion, he went out and killed one person and tried to kill two others." Police Chief Troy McGee said two boys, ages 15 and 16, were taken to St. Peter's Hospital Wednesday night. One remained hospitalized in stable condition Thursday night, and the other was flown to Harborview Medical Center in Seattle, where he was listed in serious Condition. Court records indicate the shootings occurred after Olivares-Coster intervened in a texting argument between one of the hospitalized victims and another boy over the affections of a 15-year-old girl. The other boy, identified by the initials T.W. in court records, reportedly told Olivares-Coster that one of the shooting victims had cheated on the girl and physically and verbally abused her in the past. The hospitalized victims told detectives that on Wednesday evening, Olivares-Coster met with the three shooting victims and told them they were to follow him up a hill where they would meet T.W. for the fight. However, when they arrived, the victims said Olivares-Coster stated, "I'm not going to fight fair," and then shot Andrewski in the head before shooting the other two. According to an affidavit filed by Deputy County Attorney Melissa Broch, an area resident reported witnessing the shootings. "The shot male fell to the ground face forward," the witness reported. "The fallen male lay perfectly still as if he was dead. Seconds later, two more men appeared, running down the hill past the first victim headed toward Rodney Street. The shooter fired one shot that brought one of the running men to his knees. "The man faced the shooter and said, 'Please, just leave me alone,'" Broch wrote in the affidavit. "The shooter then shot the second man twice more at close range from a standing position." One of the surviving shooting victims was shot in the head and twice in the chest, while the other was shot in the knee, both arms, both shoulders and the buttocks, court records said. The shootings happened just after 9 p.m. Wednesday near the corner of Clancy and South Rodney streets in the southwestern part of the city. The suspect reportedly fled on a mountain bike and officers searched for him through the night. Olivares-Coster was apprehended in a vehicle on Rodney Street at 8:25 a.m. Thursday, McGee said. A hearing is scheduled for June 18 to decide whether further proceedings should be held in District Court or Youth Court.