Four people, including a police officer and a gunman, were killed Monday following a shooting at a hospital in Chicago.

The Cook County Medical Examiner's office said four people died in the shooting at Mercy Hospital, according to the Associated Press.

A spokesman for the Chicago Police Department wrote in a tweet that the officer who died was Samuel Jimenez. 

One of the other victims in the shooting was the suspected gunman's girlfriend, according to the Chicago Tribune.

Mercy Hospital wrote in a tweet Monday evening that Chicago police had "secured the hospital and patients are safe."

Sen. Dick DurbinRichard (Dick) Joseph DurbinBipartisan senators doubt ruling striking down ObamaCare Durbin: Attorneys general who led ObamaCare lawsuit 'didn’t do the Republican Party any favor' Senate heads toward floor fight on criminal justice bill MORE (D-Ill.) said in a tweet Monday that his "heart is with" the hospital.

"My heart is with Mercy Hospital in Chicago tonight. I am praying for the victims, their families, and those who were injured during the shooting this afternoon. And I am extremely grateful to the Chicago Police Department who responded with bravery," Durbin wrote.

-Updated 9:25 p.m.