The Naval Station Great Lakes was on lockdown for several hours Friday morning as authorities looked for a "gate runner" just before a graduation ceremony was set to take place.
The station posted a message on Facebook just after 7 a.m. urging people "take cover in nearest building or structure." Those inside were told to "run, hide, fight" and "await instruction."
All gates were closed at the facility.
Sgt. Christopher Covelli with the Lake County Sheriff's office said a car crashed in front of a gate at the facility and authorities were searching for a person inside the station.
A public information officer for the station, however, said a driver went through an area where credentials are required but did not show credentials to the guard and continued into the naval station.
A post from the station around 9 a.m. Friday said the facility remained on lockdown as authorities "reacted to a minor situation involving an unauthorized entry." A K-9 unit was on site assisting with the search, according to the Lake County Sheriff’s Department.
"No one was harmed and no property was damaged," the post read.
Just before 10 a.m., the station posted that the vehicle and driver were located. The driver was taken into custody and was being questioned, officials said.
"The area is being swept by military working dogs," the post read. "Several buildings have been evacuated."
The lockdown was later lifted, a spokesperson for the station said, but the east entrance, however, remained closed as security was heightened at other locations.
A message on the station's website stated the graduation ceremony was being delayed.
Check back for more on this developing story.