One witness said they have been moved inside a storage area, and have been asked not to use their phones.
Police have scrambled to the hospital and are thought to be hunting an individual.
Troy Police Department tweeted: “We are investigating a threats complaint at Troy Beaumont Hospital.
“The hospital has initiated a lockdown.”
A hospital spokesperson said in a statement that there was “an active threat of violence.”
“Due to active threat of violence, Beaumont Troy is currently on lockdown.
“Visitors can leave but won’t be permitted back in.
“Patients who arrive via ambulance, have life-threatening injuries or are in labour are permitted only through the Emergency entrance.”
More to follow…