UPDATE 4:35 p.m. EST: The name of the alleged shooter has been revealed. CNN reports that it is Mohammed Youssef Abdulazeez, age 24 or 25.

"We are looking at every possible avenue," said FBI special agent in charge Ed Reinhold, "whether it was terrorism -- whether it was domestic, international -- or whether it was a simple criminal act."

Original story:

A gunman opened fire Thursday morning at two military recruiting centers in Chattanooga, Tennessee, killing four Marines before police shot and killed the alleged shooter. The names of those involved have not been released at this time.

United States Attorney Bill Killian told reporters that the events were "acts of domestic terrorism," though the FBI said it was still investigating. "We are looking at every possible avenue, whether it was terrorism -- whether it was domestic, international -- or whether it was a simple, criminal act," said the FBI's special agent in charge, Ed Reinhold.

Footage from the scene outside the first location showed multiple bullet holes in the glass front doors of the recruiting center. The gunman was described as a white male driving an open-top Ford Mustang, though this has not been confirmed.

This post will be updated as further information comes in.