"Tonight around 5:30 p.m. officers arrived to a call of shots fired at the area of 202 W. Lincoln," Amat said during a news conference, adding that officers encountered gunshots at the scene.

An officer-involved shooting occurred and a suspect was transported to the hospital, Amat said. The suspect sustained a gunshot wound and is critical condition, she said.

The department did not give any other information about the suspect or about the victims.

This is at least the 20th mass shooting since the Atlanta-area spa attacks two weeks ago that left eight people dead. CNN defines a mass shooting as a shooting incident which results in four or more casualties (dead or wounded), excluding the shooter.

"I can tell you that we haven't had an incident like this in the city of Orange since 1997," Amat said. "It's just such a tragedy for the victims, their families, our community and our police department."

One firearm was recovered from the scene, Amat said.

News of the mass shooting drew immediate condemnation.

"Horrifying and heartbreaking. Our hearts are with the families impacted by this terrible tragedy tonight," California Governor Gavin Newsom said in a tweet.

California Rep. Katie Porter said she and her team are monitoring the situation.

"I'm deeply saddened by reports of a mass shooting in Orange County, and I'm continuing to keep victims and their loved ones in my thoughts as we continue to learn more," Porter said in a tweet.

The FBI Los Angeles division has confirmed it responded to the shooting in a routine manner but that the Orange Police Department was the lead investigative agency.