The U.S. Justice Department has opened a civil rights investigation into a fatal officer-involved shooting in South Carolina.

The department's civil rights division, the FBI office in Columbia, South Carolina, and the U.S. attorney for the state have launched the probe into the shooting of 19-year-old Zachary Hammond, Justice Department spokeswoman Dena Iverson announced Wednesday.

Hammond was shot by a police officer on July 26 while in the parking lot of a Hardee's fast-food restaurant in Seneca, according to Eric Bland, one of the attorneys representing the late teen's family.

"The investigation will run parallel to the state's investigation," said Iverson, referring to the South Carolina Law Enforcement Division, which also is looking into the case.

Seneca Police Chief John Covington told CNN affiliate WHNS that Lt. Mark Tiller, a uniformed officer conducting a drug investigation, stepped out of a marked vehicle with a gun drawn and walked toward Hammond's car.

The officer opened fire -- in self-defense, police say -- after the unarmed teen accelerated and drove toward the officer.

Authorities found a small amount of marijuana in the front passenger compartment in Hammond's car.