BOSTON -- A Massachusetts General Hospital psychiatric center patient stabbed a doctor inside a Boston office building Tuesday before being shot and killed by an off-duty security guard.

The doctor, who the hospital identified as Dr. Astrid Desrosiers, of Belmont, was attacked by her patient, Jay Carciero, 37, of Reading at the hospital's Bipolar Clinic and Research Program at about 2 p.m. on the fifth floor of 50 Staniford St.

"While being seen by a physician, (the patient) attacked the physician with a knife and stabbed her. During the course of the incident, an off-duty security officer who was armed interceded," Boston Police Commissioner Ed Davis said.

A security guard, who happened to be in the building at the time, ordered Carciero, a father of four, to drop the knife, but when he refused, he was shot and killed. A weapon has been confiscated.

"Certainly heroic. We are happy he was here," hospital spokeswoman Bonnie Michaelman said.

Witnesses said they saw a man and a woman wheeled out of the building on stretchers. Arthur Frigault and his wife, Karen Heicox, were on the sixth floor at the time of the shooting.

"One (victim) was wheeled out here, and one came out of the foyer. There was a woman and she was all bloody. She was all covered up," Frigault said.

Desrosiers is an instructor in psychiatry at Harvard Medical School who worked at the clinic. The hospital said she's been a physician for several years.

"Dr. Desrosiers has spent her career providing extraordinary care and treatment to patients who are among the most vulnerable and those with the most severe psychiatric disorders," Peter Slavin, hospital president, said in a statement.

She was taken to Massachusetts General Hospital, where she was listed in stable condition. Sources told NewsCenter 5 that she suffered chest and abdominal wounds.

Police said it's unclear whether Carciero brought the knife with him or if he took it from the doctor's office. Carciero's attorney, Jim Perulo, told NewsCenter 5 that he had been receiving treatment, but did not disclose his medical condition.

""He was being treated, but beyond that we're not saying anything because we haven't determined all of the details," Davis said.

The building was locked down, and police cordoned off nearby streets. Employees and patients were told that they could not leave their offices.

"No one else has anything to fear. The Boston police responded here immediately with one of our tactical units. They entered the facility and secured the place within minutes," Davis said.

Last week, a repeat sex offender was accused of assaulting a female employee inside a bathroom at Massachusetts General Hospital. During a hearing Tuesday, the suspect, David Flavell, was ordered to undergo a mental competency evaluation.

In 2003, a cardiologist was killed in a Massachusetts General Hospital lab by a co-worker who then killed herself. The woman, Colleen Mitchell, shot Dr. Brian McGovern several times in a small office inside the lab.

At the time, officials said Mitchell was suffering from depression. McGovern, a native of Ireland, had worked at MGH for more than 20 years.