Police are investigating reports that objects were thrown from a bridge at vehicles travelling along the M25 in Essex.
They received five reports between 11.15pm on Monday August 17 and 9.55pm Tuesday August 18, after stones had struck vehicles travelling between junctions 27 and 28.
It is understood that they were thrown from a bridge.
Two of the vehicles involved were HGVs, with the drivers reporting damage to their windscreens.
A group of people, described as being aged in their early teens, were seen in area.
Chief Inspector Darren Deex said: ”We are investing five reports in a short period time of objects being thrown at vehicles travelling along one of the country’s busiest roads.
“Fortunately, no one was injured but the actions of the people involved put motorists at serious risk of harm.
“I understand that some children, possibly in their early teens, were seen on the bridge.
“I urge parents and guardians to help educate your children or young people in your home about the consequences of their actions for them and for innocent motorists.
“If you live nearby, please ask yourself, do you know what your children are up to? Could they be their friends be involved in this behaviour?
“We are investigating these reports and we are looking to identify those involved, if you have information, please call us on 101 or visit www.essex.police.uk.
“Additionally, please call Crimestoppers anonymously on 0800 555 111.”