Atlanta mass shooting updates: Victims identified

The suspect, Deion Patterson, has been apprehended following an hourslong manhunt, Atlanta police said.

Police plan to hold a press briefing at 8:15 p.m.

Police in Cobb County said Deion Patterson was seen on video in the county around 12:30 p.m. ET, roughly 20 minutes after the shooting, though it's unclear if he's still in the area.

Cobb County Police Sgt. Wayne Delk said during a press briefing that after learning Patterson might be in the area, his team checked flock cameras and "did discover that the vehicle had entered Cobb County," located northwest of Midtown Atlanta, where the shooting occurred.

"Around 12:30 p.m., we did spot what appeared to be a suspect in this area, which is why we have such a heavy presence," Delk said.

Police did not discover the video footage until around 2:30 p.m., and Delk acknowledged it's unclear if Patterson is still in the county.

"He might still be in the area," he said.

The vehicle Patterson was believed to be driving was recovered by Atlanta police in a parking garage, Delk said.

-ABC News' Will McDuffie

Of the four women who were shot and injured in the medical facility waiting room, three of them are considered "critically ill" and are in the intensive care unit, according to Dr. Robert Jansen, the chief medical officer at Grady Health.

The most seriously injured patient remains in the operating room, Jansen said, while a second victim has completed an operation.

Another victim underwent an interventional radiology procedure, which is used to repair vascular injuries, and will need more procedures in the future, he said.

The fourth patient is considered stable, he said.

-ABC News' Darren Reynolds

Sen. Raphael Warnock, D-Ga., gave a passionate speech on the Senate floor in the wake of the latest mass shooting to strike the nation, this one unfolding in his "own backyard."

"I rise today in shock and sorrow and in grief for my home state," Warnock said.

Warnock noted that his two children were under lockdown at school on Wednesday amid the ongoing hunt for the Atlanta gunman.

"We behave as if this is normal -- it is not normal. It is not right for us to live in a nation where nobody is safe, no matter where they are. We're not safe in our schools. We're not safe in our workplaces. We're not safe at the grocery store. We're not safe at movie theaters. We're not safe at spas. We're not safe in our houses of worship. There is no sanctuary in the sanctuary. We're not safe at concerts. We're not safe at banks. We're not safe at parades. We're not safe in our own yards and in our own homes," he said. "And now, today, we can add medical facilities to that list."

He warned, "It's only a matter of time that this kind of tragedy comes knocking on your door."

As a pastor, Warnock said, "I'm praying for those who are affected by this tragedy," but he stressed, "It is a contradiction to say that you are thinking and praying and do nothing. … We pray by taking action."

Warnock said he's "pleading" with his colleagues in Congress to pass stricter gun reforms to "do everything we can to protect all of us and certainly all of our children."

-ABC News' Trish Turner