Carl Wilson was shot while walking on Little School Road, which is south of Interstate 20 along the Arlington-Kennedale border.
Police originally said that they believed Wilson was targeted because of an argument that started at school, but Arlington ISD clarified that there was no fight at school Monday; merely a discussion during lunch between Wilson and other students.
Police interviewed several witnesses and have gotten some solid leads.
They haven't taken anyone into custody, but they have identified and found a possible suspect vehicle.
Some witnesses say they saw a black Lincoln Navigator leaving the scene.
Police say they got an anonymous tip and seized it in Grand Prairie. They're still looking for the driver, whom they say has ties to an Arlington gang.
Police have also emphasized that Wilson was not a gang member.
Wilson's family members said he was a popular linebacker and running back for Arlington Martin.
The 18-year-old also had his own apartment and custody of his 1-year-old son, King. He reportedly planned to play football at Kilgore College next year.
Arlington Martin Principal Marlene Roddy announced Wilson's murder and held a moment of silence for him Tuesday morning.
"Students and staff, I'm extremely sad to tell you that we lost one of our classmates and our student yesterday," she said.
Friends of Wilson have posted numerous pictures of him on social media. Many wrote how stunned they were to learn the news hours after passing him in the hallway.
"I knew something like this was gonna happen, because this group of guys has been terrorizing south Arlington for a while, at least for two years, because they've been into it with my son," said Kenneth Levy, whose son was friends with Wilson.
Levy said Wilson was a respectful and kind young man.
Principal Roddy said lots of rumors about what happened have been floating around the campus and on social media. Because of that, the school will have extra security and counselors on hand to help.
A vigil for Wilson was held at the school Tuesday evening, where his classmates and teachers shared stories about him and prayers, then released balloons in his honor.
"It pains me to see he's not going to be here with us anymore, but his memory will live on through everybody who showed up here tonight and everybody who didn't have the chance to," said classmate Cameron Cooper.
Wilson's funeral will be held Saturday at Serenity Funeral Home. A GoFundMe account has been set up to help with arrangements.
Anyone with information about the crime or suspects should call Kennedale police.
This is Kennedale's first murder of 2015. The last murder, in November, was the first in five years.