The white sheriff's deputy caught on video flipping a black high school student out of her classroom chair in Columbia, South Carolina, will be fired, MSNBC reported on Wednesday.

MSNBC, citing sources, said the dismissal of officer Ben Fields is expected to be announced during a noon news conference called by Richland County Sheriff Leon Lott to reveal the findings of his agency's internal investigation into Monday's incident at Spring Valley High School.

A spokesman for the sheriff's office declined to comment on the report but confirmed the deputy's future on the force will be discussed.

Fields, 34, was suspended without pay after videos filmed by students showed him slamming a 16-year-old girl to the ground and dragging her across a classroom after she apparently refused to hand over her mobile phone to a teacher.

The student, who Lott said hit the officer during the altercation, was arrested on a charge of disturbing schools. Lott said she was not hurt.

But the girl's lawyer told ABC's Good Morning America on Wednesday that she suffered injuries after being "brutally attacked."

"She now has a cast on her arm, she has neck and back injuries," lawyer Todd Rutherford said. "She has a Band-Aid on her forehead where she suffered rug burn."

Lonnie Randolph, president of the South Carolina chapter of the National Association for the Advancement of Colored People, said Fields should be criminally charged.

The Federal Bureau of Investigation and Justice Department have opened a civil rights probe into the arrest, which prompted a hashtag #AssaultAtSpringValleyHigh and widespread outrage on social media and in Columbia after the video footage went viral.

Lott, who cut short a trip to a law enforcement conference to deal with the incident, promised on Tuesday the investigation into whether Fields followed department protocol for school resource officers would be swift.

"This is not something that should drag out," Lott told reporters.

The sheriff said a teacher and administrator who witnessed the encounter felt the officer acted appropriately.

Fields, who has not commented on the incident, has worked for the sheriff's office since 2004 and joined its school resource officer program in 2008. An elementary school where he is also assigned presented him with a "Culture of Excellence Award" last year.

(Additional reporting and writing by Colleen Jenkins in Winston-Salem, N.C.; Editing by James Dalgleish)