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

The manhunt is ongoing for the mass shooting suspect, 24-year-old Deion Patterson, Atlanta police said at a news conference Wednesday afternoon. Police said the gun has not been recovered.

The shooting, which unfolded in a medical center waiting room, killed a 39-year-old woman, police said.

The four injured victims, who are all women, are "fighting for their lives," Atlanta Mayor Andre Dickens said. They are ages 71, 56, 39 and 25, police said.

"As soon as possible I'll be in touch with the families of the victims," he said.

Patterson's family is cooperating with the investigation, police said.

Patterson joined the Coast Guard in July 2018 and was discharged from active duty in January 2023, the Coast Guard said.

Dr. Timothy Simons was performing surgery one floor above the scene where the shooting unfolded.

He told ABC News he completed the surgery and then sheltered in place.

When police came to clear the building floor by floor, Simons said he was told to put his hands up to verify that he was not the shooter.

"Then they escorted us all down the stairs," he said.

-ABC News' Janice McDonald

Of the four people who were shot and injured, three are in critical condition and one is in the emergency department, according to hospital officials.

All four are adults, officials said.