Police in Keller say they were called to Kohl's department store at about 4 p.m. Thursday. The man had been detained by store security. As police officer Johnathan Hicks led the suspect to a squad car, police say the suspect began fighting with the officer.
Hicks fired his weapon four times, though it's not yet clear how many times the man was shot.
He died at a Fort Worth hospital.
Police have not identified the suspect, but say he appeared to be about 40 years old.
Hicks was treated for minor injuries.