The children were taken to Le Bonheur Children's Hospital in Memphis, and two Covington Police officers were taken to Baptist Hospital-Tipton, for smoke inhalation.
Fire crews were called to the Broadmeadows apartments at 3:15 for a call that two children were tapped inside the burning apartment.
Neighbors and police officers stepped in to help, the fire department said. One woman gave a baseball bat to a young man, who used it to bust a window. Another man climbed on top of his vehicle to get inside the apartment.
"The heroic efforts of everyone involved in this incident today is the staple of what we do when we have someone in need," the department said in a statement.
The fire was contained to one apartment.