Officers say they responded to Main Street near H Street after a report of shots fired.
They found one victim suffering from a gunshot wound on Main Street, two others on H Street, and the fourth on 18th Street.
The victims have all been rushed to Modesto hospitals.
One of them is in critical condition and the other three are expected to be OK. .
Officers are still working to determine what happened, and identify a suspect. It's not yet know if the shooting was gang-related.