Editor's note: Police originally identified the man as a 46-year-old.

ST. LOUIS – Police are investigating after a security guard inside the Center for Advanced Medicine fired several shots at a patient who was armed with a knife Thursday morning.

26-year-old Andrew Merryman man was pronounced dead at the scene. Police believe he was there for an appointment. Two security guards approached him and issued warnings before firing shots.

The man’s wife was there during the shooting. It’s unclear what the his motive was, police say.

The Center for Advanced Medicine is located on the 14th floor at the Barnes-Jewish Hospital campus.

St. Louis Children’s Hospital was placed on lockdown as a precautionary measure. As of 11:20 a.m., the lockdown has been lifted.

No other details have been provided.