Johnson, a true freshman receiver out of Dallas Skyline High School, was last seen leaving his residence in College Station at approximately 6 p.m. ET Monday, according to the UPD.
"I'm asking anyone … anyone … to just provide any piece of information," his mother, Linda Hanks, said through tears Wednesday night outside her South Dallas home, WFAA.com reported.
The station reported Hanks visited Johnson last week, then received a text Monday that he had missed class and practice.
"If I could transfer some of the faith I have in God to Thomas -- to let him know how much I love him, and others are so supportive of him and love him, too," Hanks said, according to WFAA.com. "I'm asking God to do that right now, to touch him in a special way.
"Thomas has been building over the years a relationship with Christ. It's really gotten strong in the last couple of months. So, I know God is in this. And if he's in it, it's going to be OK. But that doesn't stop me from crying, and it doesn't stop me from wondering, and it doesn't help me sleep."
Texas A&M coach Kevin Sumlin expressed the team and the school's concern for Johnson's welfare in a statement released by the school on Wednesday night.
"All of us are obviously very concerned about the safety and well-being of Thomas Johnson, who has been missing since Monday evening," Sumlin said in the statement. "Authorities are working closely with his family, friends and law enforcement agencies to help locate him. Thomas is a tremendous student-athlete, greatly admired by his fellow teammates and all of us on the coaching staff. If anyone has any current information about him or knows of his whereabouts, please contact his family or law enforcement authorities immediately. We pray for his quick and safe return."
Texas A&M freshman defensive back De'Vante Harris also posted on his Twitter account Wednesday night: "Everybody help please find my cousin Thomas. If y'all find out anything, please call [police]."
Anyone with information on Johnson's whereabouts should contact UPD at (979) 845-2345. The police department said he was last seen wearing a black jacket, black shorts and gray shoes, and that he might have traveled to the Dallas area.
The 5-foot-11, 180-pound Johnson has caught 30 passes for 339 yards and a touchdown in 10 games (including two starts) this season.