A bomb threat forced WellStar Kennestone Hospital to go on lockdown for about three hours Wednesday, though medical services continued inside.

By early afternoon, things were back to normal at the busy Marietta hospital.

But, the work continued for investigators, who want to determine who called in the threat, forcing the evacuation.

“We are conducting a full-blown investigation,” Officer Brittany Wallace with Marietta police said Wednesday afternoon.

The threat was phoned in at 10:02 a.m. to the non-emergency line for Cobb County police, Officer Alicia Chilton said. The Cobb police K-9 unit and sheriff’s office assisted with the search at the hospital, along with a Kennestaw State University K-9 and Kennestone security.

During the hospital lockdown the main Church Street entrance was blocked. No one was allowed to enter the hospital, but patients inside continued to receive treatment, the WellStar hospital system said late Wednesday.

“WellStar is prepared for situations like this,” WellStar said. “We have policies and procedures in place to keep our patients, team members and community safe.”

Shortly before 2 p.m, the hospital was cleared and no explosive device was located.

The threat remained under investigation late Wednesday.