Hundreds of people say they have been hit with snowballs
The police in the north west have received hundreds of complaints that cars have been attacked by people throwing snowballs.
The PSNI said those involved were "reckless" and "stupid".
In one incident, a gang opened the door of a taxi on Madam's Bank Road in Londonderry and pelted Jonathan Hagan, who has cerebral palsy, with snowballs.
The attacks began after heavy snow fell in the north west on Saturday night.
Driving conditions remain treacherous across the region.
Mr Hagan's mother Julie said she was "appalled" by the attack on her son, and wanted those responsible to explain themselves.
"Why would you do that to anybody?"
"Come and talk to Jonathan and just tell us why.
"Let them see how hard it is for him to move about or even get his hand to his face.
"He couldn't protect himself," she said.
Another man, who did not want to be named, said his car was pelted with snowballs as he drove through Creggan in Derry on Sunday.
"They stand and wait to ambush you with a barrage of snowballs.
"They're not children - there's no humour there, there's no fun, they're out to do damage.
"You're afraid driving past them because you know you're going to be hit with the snowballs, and they're thrown by older ones who can put a bit of force behind it," he said.