Hospitals, like schools, are not typically designed to guard against the threat of a determined gunman entering the building to take lives.

The vulnerability of health care facilities was highlighted by a shooter who killed four people and then himself Wednesday at a hospital in Tulsa, Oklahoma. The assailant got inside a building on the Saint Francis Hospital campus with little trouble, just hours after buying an AR-style rifle, authorities said.

Here's a look at what's known about security at the Tulsa facility and other American hospitals:

DID THE GUNMAN HAVE TO PASS THROUGH SECURITY?

No, t...