The 2-year-old was in critical condition, Seattle police spokeswoman Detective Valerie Carson said. No arrests had been made in connection with the shooting.
Police responded to reports of shots fired at 23rd Avenue South and Jackson just before 3:30 p.m. near a Walgreens pharmacy. The responding officers found shell casings and blood, KOMO-TV reported.
Police advised drivers in the area to "seek alternate routes" amid an ongoing investigation.
The wounded people were transported to Harborview Medical Center and Swedish Hospital Cherry Hill for treatment. Earlier reports indicated that there were four victims, but police later said there were three.
Fox News has reached out to the Seattle Police Department seeking more information.
This is a developing story. Check back for updates.