RICHMOND -- Two young men caught in a flurry of bullets Tuesday afternoon are expected to survive, Richmond police said.

The city's ShotSpotter audio gunshot-detection system pinpointed 24 rounds fired at 1:15 p.m. in the 600 block of Fifth Street, said Richmond police Capt. Mark Gagan.

Police responding to the scene in the Iron Triangle neighborhood found spent shell casings but no victims, Gagan said.

"The gunshot victims transported themselves to Kaiser hospital, and one was airlifted to (John Muir Medical Center in Walnut Creek) in critical condition," Gagan said. The other victim is at Kaiser in serious condition, Gagan said.

Police believe that the brazen daytime shooting is gang-related and are concerned that it could spark retaliation.

Both victims were described as "black males in their early 20s" by police. An abandoned vehicle that police believe was used in the shooting was recovered Tuesday afternoon.

"Events like this get our full attention because they tend to prompt retaliatory violence," Gagan said. "We will deploy extra patrols tonight and have alerted our community anti-violence partners."

Contact Robert Rogers at 510-262-2726 or rrogers@bayareanewsgroup.com. Follow him at Twitter.com/SFBaynewsrogers.