A 27-year-old man was struck by a police vehicle and killed early Tuesday while trying to cross a busy DeKalb County street.

The man, identified by police as Clinton Hightower, was attempting to cross Memorial Drive at West Mountain Street when he was struck by a patrol car driven by Officer Jason Copper, Mekka Parish, spokesman for DeKalb County police, told the AJC Tuesday afternoon.

Hightower was not in a crosswalk at the time he was struck, Parish said.

A witness told Channel 2 Action News that the officer did not have his emergency lights or siren activated.

Police said Tuesday afternoon the officer was headed to the homicide investigation at the Starlight Six Drive-In.

"The investigation into this accident is ongoing," Parish said in a statement to the AJC. "Detectives are looking into when the officer’s lights were activated and if the siren was on as well as it will determine how fast he was traveling."

Police have not released the name of the officer involved.

-- Staff writer Mike Morris contributed to this article.