Passengers were evacuated from a bus in Edinburgh on Monday when it was engulfed in flames.
Police say the blaze was started 'deliberately' and have released a description of the suspect.
STV News reports that the fire broke out on the bus on Oxgangs Road. No one was injured and firefighters managed to control the blaze.
According to the BBC, a youth was seen getting off the bus at Oxgangs library before the fire was reported.
He is described as white, 14-16 years old and wearing a dark hooded top.
DI Rory Hamilton said: "The bus has suffered extensive damage, as a result of this fire, which we believe was started deliberately. Luckily no one was injured as a result of this reckless act.
"We are appealing to anyone who noticed any suspicious activity on the number 4 bus or in the area of Oxgangs Road from 10.30pm on Monday night, when the fire was reported, to contact police."
Fire destroys 35 buses at depot in Cornwall
Passengers evacuated after bus catches fire at Norwich Airport