NEW YORK (AFP) - A doctor was critically injured when a man opened fire on Tuesday at a hospital in Boston, police in the US city said, adding that the suspected shooter then killed himself.

The incident occurred shortly before noon at Brigham and Women's Hospital, where the situation was now "under control", Boston police chief William Evans said at a press conference.

Police received several 911 calls starting around 11.00am reporting shots fired at the prestigious hospital's cardiovascular centre, across from the main entrance.

"By 11.07, we received another call of a doctor being shot and people barricaded themselves inside offices," Mr Evans said.

The doctor injuries are "life-threatening", he added.

When police arrived on the scene, "they found who we believe to be the suspect inside the examining room, with what appears at this time clearly a self-inflicted gunshot" wound, Mr Evans said.

"Beside him there was what we believe to be the weapon used in this tragedy."