Police were called to a Circle K in Yakima, Washington, about 3:30 am when three people, who have not been identified, were found dead, Chief Matt Murray told reporters.
The injury to the teacher, a woman in her 30s, was considered life-threatening, though she had shown some improvement in the hospital, said Police Chief Steve Drew.
It's still unclear if the shooter died of self-inflicted injuries.
The suspect is Ezekiel Kelly and he was apprehended on Wednesday.
The sheriff's office didn't identify those killed or give details about what led to the shooting.
It was unclear how the shooter died or what prompted the deadly assault.
The police clarified that the accused sported no personal grudges against the victim.
He was nabbed at the Mumbai International airport while trying to flee to Dubai on a fake passport.
According to the police, the goons were provoked as Manikandan did not seal a punctured tyre. They allegedly hit him on the face with the air gun and shot at his leg.
The champion shooter, who has taken to mentoring a few years ago, called it a "torrid 24 hours".