Fort Worth police Sgt. Raymond Bush confirmed to ESPN.com that Fields is under investigation for allegedly aiming a gun at the woman Sunday and threatening her.
Yahoo! Sports first reported that Fields was under investigation. Bush, however, said Tuesday that Fields had not been arrested.
Last week, Fields was voted the Big 12's preseason Defensive Player of the Year.
TCU released a statement Tuesday:
"Devonte Fields has been separated from the university pending results of an investigation into the allegations against him," it read. "The university does not tolerate harassment or misconduct by a student. The university discipline process will be implemented, which may result in disciplinary action from the university above and beyond any legal consequences the student might face."
The school later clarified "separated" to mean that Fields must stay away from both the school and the team until the police investigation is completed.
According to the Fort Worth Star-Telegram, police had been called to a domestic disturbance about 3:30 a.m. Sunday in Fort Worth. There, Haley Brown, 20, told police that Fields had been standing outside a bedroom window listening to her talk to a mutual male friend. Brown said Fields punched out the window of their friend's bedroom and began yelling at her. That's when, Brown told police, Fields pointed a gun at her and yelled, "I should blast you!"
Police told the Star-Telegram that Fields then went to the home's front door and was let inside by their mutual friend's roommate. Brown told police that soon after Fields punched her in the face.
"Whether it be a football player or any other student on this campus, if anything like this happened and they were investigating it, they would do the same thing, which basically that means you're not allowed on campus," TCU coach Gary Patterson said Tuesday.
"Obviously, it's disappointing to me that we'd be in that situation," Patterson said. "Nothing I can do, just make sure that I let justice do its course."
In January, Fields reported to police that he had been robbed and threatened in a struggle that included gunfire. Fields, however, later told officers that he didn't want them to search his home and that he didn't want to press any charges.
Fields was The Associated Press' Big 12 Defensive Player of the Year in 2012. He was suspended for the first two games of the 2013 season for a violation of team rules and wound up playing in only two games because of a foot injury.
Information from The Associated Press was used in this report.