[Updated at 3:12 p.m.] The gunman in Thursday's Johns Hopkins shooting - identified as Warren Davis, 50 - shot himself and his mother, who was being treated at the hospital, Baltimore's police commissioner said.
Davis was standing outside room 873 in the Nelson building, where he was being briefed by a doctor about the condition of his mother, Commissioner Frederick H. Bealefeld said.
"Mr. Davis was receiving some news about the care and condition of his mother just outside the doorway to that room when he became emotionally distraught," the commissioner said.
During the conversation, Davis pulled a small, semiautomatic gun from his waistband and shot the doctor once in the lower chest/upper abdomen, he said.
Within minutes, a tactical team later entered the hospital and found Davis dead from a self-inflicted gunshot wound. His mother had also been killed, Bealefeld said.
[Updated 2:33 p.m.] Baltimore police now say the incident at Johns Hopkins Hospital is a murder-suicide.
The gunman, who shot a doctor in the abdomen, killed himself as well as someone else. It was unclear who else was killed, but sources say the wounded doctor is expected to recover.
Some media outlets, including The Baltimore Sun, are saying that the gunman shot his mother, who was being treated at the hospital.
[Updated 2:23 p.m.] There are now conflicting reports on how the shooter at Johns Hopkins Hospital died.
Some media outlets are reporting the gunmen shot himself, but CNN has not been able to confirm the reports. Police earlier told CNN that police shot the gunman.
[Updated 2:04 p.m.] Minutes after police announced the shooter at Johns Hopkins Hospital was killed by a tactical team, police spokesman Anthony Guglielmi said, "The situation is resolved."
SWAT team members leaving the scene told CNN the same.
The situation has now moved from a tactical operation to a crime scene, Guglielmi said.
[Updated at 1:56 p.m.] Employees at the scene of the hospital shooting tell CNN affiliate WBAL that the shooter was unhappy with how his mother was being treated and that the wounded doctor was shot during surgery.
A reporter for The Baltimore Sun told CNN earlier that he had heard similar information from his sources.
One employee, Cynell Robertson, told WBAL that the moments after the doctor was shot were frightening.
"My boss came running in to tell me to stay put where I'm at, there's a guy running around with a gun and we didn't know what he's going to do,"she told WBAL.
Police have said the shooter was killed by police, but no further information was immediately available.
[Updated at 1:51 p.m.] Police say the suspect in the Johns Hopkins Hospital shooting is dead. He was shot by police, authorities said.
[Updated at 1:40 p.m.] Baltimore police say the situation at Johns Hopkins Hospital is contained, but "we're still trying to gain control of the suspect."
Police spokesman Anthony Guglielmi described the suspect only as an African-American male in his 30s. He further said police have heard reports the shooter is in a room, barricaded with a family member.
Guglielmi refrained from providing information on the shooter's location because there are televisions throughout the hospital.
He said there was no risk to the general public or patients and that the FBI is on standby. He wouldn't discuss whether police were in contact with the shooter.
As for the injured doctor, Guglielmi said he suffered abdominal injuries.
"He's in surgery as we speak, but he is going to be OK," he said.
[Updated at 1:14 p.m.] Criminal profiler Pat Brown tells CNN she believes the incident at Johns Hopkins could end "better than most situations" because the shooter does not appear to be a mass murderer.
The shooter may even realize he's made a huge mistake, and he might be scared because he knows he's trapped, Brown said.
A hospital employee, who said she left the hospital shortly before noon, told CNN affiliate WBAL that her shift isn't over for several hours. She has not been told to go home and she has not been able to return to work, she said.
"I really am scared," she told the station.
[Updated at 1:03 p.m.] A statement from Johns Hopkins Hospital says the doctor who was shot is a "faculty physician" and that confidentiality policies prohibit the hospital from releasing more information.
[Updated at 12:42 p.m.] Police say they know where the Johns Hopkins suspect is and have him cornered.
However, said police spokesman Anthony Guglielmi, there is no information on whether the shooter has hostages.
Guglielmi said tactical units are on the scene, but the emergency room remains open and the incident is contained to one floor.
He further said he has learned that the doctor's condition has been upgraded, and his injuries now do not appear life-threatening.
Justin Fenton, a crime reporter for The Baltimore Sun who is across the street from the hospital, said a source tells him the shooter is upset about his mother, who is being treated at Johns Hopkins.
[Updated at 12:35 p.m.] Baltimore police say a SWAT team is on the scene as they attempt to apprehend the shooter.
[Updated at 12:29 p.m.] Baltimore police say earlier reports that a suspect was in custody in the shooting at Johns Hopkins Hospital were incorrect.
Baltimore Police Department spokesman Anthony Guglielmi said authorities also have no information on a motive or the relationship between the suspect and a doctor who was critically wounded.
[Updated at 12:25 p.m.] A shooter who critically injured a doctor at Johns Hopkins Hospital in east Baltimore, Maryland, has been "subdued and disarmed," according to a hospital spokesman.
Police reported that a doctor had been shot, and Johns Hopkins spokesman Gary Stephenson said the injured doctor had been taken to an operating room.
Earlier, local media said the suspect was hiding in a patient's room on the eighth floor of the hospital. CNN affiliate WMAR in Baltimore said the shooter had barricaded himself. It's unclear if the shooter was alone in the room.
Reports indicate the wounded doctor is in critical condition. Many people were evacuated, according to reports. Those who weren't evacuated were told via e-mail to stay in rooms at the hospital, which has about 1,000 beds. The e-mail further instructed them to keep room doors locked and to stay away from windows.
The hospital released a statement saying it had temporarily restricted access to the hospital's main buildings.
A witness told WMAR that the shooting happened in the hospital's Nelson Building, which is near the emergency room entrance.
Local media reports indicate the shooting occurred between 11 and 11:30 a.m.