A THUG sprayed a bus driver in the face with a fire extinguisher while an accomplice filmed the attack.
Police think the youths had carefully planned the attack to make sure they captured it on video.
Now, officers have appealed for anyone who saw what happened to come forward.
The attack happened when the 372 bus from Huddersfield town centre pulled into the stop at the top of Southfield Road in Almondbury at 5.20pm yesterday.
Two youths got on the bus while another - with the video camera - waited outside.
One of the attackers suddenly sprayed the driver in the face with the ice-cold powder.
The victim, a 49-year-old Longwood man, was shocked by unhurt.
Pc Michelle Jaques, of Huddersfield police, said: "There were a lot of people on the bus and others getting on and off.
"So quite a few would have seen what happened.
"Luckily, the driver had already put the handbrake on and some of the powder hit his partial screen.
"It may well be these youths have told friends what they have done - or even shown them the video."
The youth who sprayed the powder is white, aged 14 to 16, 5ft 2in and casually dressed.
Anyone with information or who knows who the youths are should phone Pc Jaques on 01484 436659.