6 injured in Tennessee shooting, police say

At least six people were injured on Saturday night during an exchange of gunfire in downtown Chattanooga, Tennessee, police said.

Chattanooga police officers were patrolling the downtown area at about 10:48 p.m. local time when they "observed multiple parties exchanging gunfire and numerous people fleeing the area" near 100 Cherry St.

"Our Officers began rendering aid to the victims as well as assisting others to safety," a police spokesperson said. "They were able to detain at least one person of interest in the incident in the moments after the shooting began."

Police said "several" gunshot victims were transported to local hospitals. Two individuals had life-threatening injuries, police said. Most of the victims were in their teens or early 20s, police said.

Chattanooga Mayor Kelly posted a message Sunday on Twitter, saying, the shooting was "unacceptable -- our city and our community will act."

"Last night, our city felt the terrible cost of gun violence," Kelly tweeted. "My heart is with the families whose lives have been upended by this horrific situation."

Kelly said he and the Chattanooga police chief are planning to hold a news conference on the shooting Sunday afternoon.

"We had large groups of juveniles walking around the downtown area this date and we believe it's from within that group that the shooting took place," a police spokesperson said.

This is a developing story. Please check back for updates.

ABC News' Keith Harden contributed to this report.