Deion Patterson: Everything we know about the at-large Atlanta mass shooting suspect

One person is dead and multiple people in Midtown Atlanta have been injured in what police have called an "active shooter situation."

"We are aware of multiple people injured. No suspect is in custody," the Atlanta Police Department wrote on Twitter.

Later, police confirmed one person had died in the mass shooting.

"Three have been transported to the hospital for treatment and a fourth has been pronounced deceased on scene," police tweeted. "Officers are actively searching for the suspect and any other victims."

Helicopter footage captured by WXIA-TV showed there were dozens of police on the scene of the shooting, which reportedly took place at Northside Hospital in the area of 110 W Peachtree St NW, according to police.

Atlanta Mayor Andre Dickens said he was aware and monitoring the situation while keeping in communication with law enforcement.

Police released a photo of the suspect who appears to be a young, Black man wearing a grey hoodie, black pants, grey and white sneakers, a white medical mask, and what appears to be a tan tactical bag over his abdomen.

They have named the suspect as Deion Patterson, 25.

“Based on our preliminary investigation, these are photos believed to be of the active shooter. Anyone with any information on this person’s whereabouts is asked to call 911,” Atlanta police said in a tweet. “The suspect is believed to be armed and dangerous and should not be approached.”

The security footage that captured the image of the suspect is reportedly from the Northside Hospital, where the shooting took place.

Police told CNN that the suspect is someone they are familiar with, but have not provided further details.