bystander

a person who is standing near and watching something that is happening but is not taking part in it ผู้เห็นเหตุการณ์, ผู้สังเกตการณ์

Three bystanders were also injured in the explosions.

Among the 91 dead, there were also innocent bystanders and non-violent protesters.

After the shooting, bystanders tackled the gunman, identified as a 22-year-old local resident.