TULSA, Oklahoma - Police are still looking for the man who shot and killed two people, one of whom was a Jenks High School senior, in a QuikTrip parking lot this weekend.

Kirstjan Hinrik Thorsson, 18, was sitting in the passenger seat with John White III, 37, behind the wheel, when a man shot them both in the parking lot of the QuikTrip at 71st Street and Riverside Drive.

Thorsson died at the hospital and police said White died Monday afternoon.

Detectives said it was a senseless and random act of violence. They said it appears the shooter thought White had come too close to him in traffic, and after exchanging some words, fired nine shots into the car, then took off.

Thorsson moved to Oklahoma when he was 10 years old, with his mom, older brother and younger sister. His family is from Iceland.

He was a senior at Jenks, looking forward to graduating in the spring.

"Hinrik was a little complicated. He was very artistic, good at drawing, liked to write poems, but very insecure, because he stuttered," Thorsson's grandmother, Helena Mawby said.

Mawby said, in addition to drawing or painting, Thorsson loved writing song lyrics and dreamed of going to OSU to study music.

She said he loved to talk, to express his opinions on everything from politics to current events, and had a laugh that was quite contagious.

"He had a laugh that made everyone laugh. Everybody laughed with him," Mawby said.

Mawby said the whole family is still in shock as they plan his funeral.

Thorsson had gone to QuikTrip with White, a friend of his mother. Mawby said they never dreamed something so simple would be the end of his life.

"It's such a random act—so unnecessary, you don't understand why," Mawby said.

She said she's been overwhelmed by the outpouring of support from fellow students and friends, and that Thorsson might be surprised to realize he was so well loved.

Because family is coming in from Iceland, the funeral is set for Friday afternoon.

The family believes someone in that busy parking lot had to see something - even a little detail - that might help catch the shooter, and they ask people to call police if they have information. That can be done anonymously through Crime Stoppers at 918-596-COPS.