Word spread through an Oregon hospital last month that a visitor was causing trouble in the maternity ward, and nurses were warned the man might try to abduct his partner’s newborn.

Hours later, the visitor opened fire, killing a security guard and sending patients, nurses and doctors scrambling for cover.

The shooting at Legacy Good Samaritan Medical Center in Portland was part of a wave of gun violence sweeping through U.S. hospitals and medical centers, which have struggled to adapt to the growing threats.

Such attacks have helped make health care one of the nation’s most violent fields. Data shows American health care workers now suffer more nonfatal injuries from workplace violence than workers in any other profession, including law enforcement.