Bricks and stones were hurled on to a busy bypass during yesterday evening's rush hour.
Shocked drivers alerted police after children were spotted throwing the missiles from a footbridge over the A27 at Hangleton.
There were no reports of damage or injuries but police said it was down to luck that a serious accident was avoided.
It is the second time in a week that officers have been called to the footbridge, which links Buckley Close, Hangleton, with the South Downs on the opposite side of the bypass.
Sergeant David Bettis said: "This is an incredibly dangerous thing to do and it is only a matter of luck that nobody was killed or seriously injured."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article