Update from Hopkins: The Johns Hopkins Hospital is not currently locked down, but visitors are being asked to stay out of the Nelson Building. Employees who have hospital identification badges can be in the building, but are not to try to access Nelson 8. Patients on Nelson 8 are going to be evacuated to other locations throughout the hospital.
Pregnant women in active labor should be encouraged to go to the Johns Hopkins Bayview Medical Center.
Baltimore police remain at Johns Hopkins Hospital after a gunman shot and critically wounded a doctor and is now contained to a room on the 8th floor of a building on the sprawling East Baltimore medical campus.
Police SWAT members and dozens of officers are inside and around the hospital and the CNN is reporting live from the scene. The television network has already put The Sun's Justin Fenton on air to describe events. Fenton's picture from the scene is at left; follow his Twitter updates here.
Police had blocked off many streets in the area, but they just sent out a Twitter alert noting that the situation "is isolated to one relatively small part of the hospital. Persons who have business are encouraged to come."
Details remain slim at this hour but police have confirmed that a doctor was shot but apparently did not suffer life-threatening injuries. A nurse told reporters that the gunman was upset at the treatment of his mother and threatened to jump out of a window. Police just Twittered that "motive unclear at present."
A police officer had reported early in the confrontation that the man was holding his mother hostage, but police have not confirmed that there is any hostage involved. The name of the doctor has not been released.
Here is one report: