A bus driver travelling on a motorway was nearly killed when a 10 kilogram tub of adhesive was thrown from an overhead bridge, police have said.
The pot smashed through the windscreen and hit the 60-year-old at the wheel of the single decker on the M80 on Saturday evening.
The driver lost all power of the bus after it smashed the steering column but he was able to slow down and bring the vehicle to a stop at the side of the motorway.
The tub is thought to have been stolen from a nearby building site.
Chief Inspector Glen Bland from Strathclyde Police said: "It is no understatement to say that it is only sheer luck which stopped this incident being much worse and the driver counts himself lucky that he was not severely injured or killed as a result of this completely senseless act on one of Scotland's busiest roads.
"It's to the driver's credit that he managed to avoid other vehicles and stop the bus at the edge of the motorway."
The incident happened at junction 6 northbound at around 9.50pm. The driver suffered minor injuries but was badly shaken, police said.
Officers are viewing CCTV footage as they hunt for the culprit. The large tub may have been stolen from a nearby building site close to Our Ladies High School in Dowanfield Road in Cumbernauld.
"It is vital we trace those responsible for carrying out such a dangerous act and I am appealing to drivers who were on the M80 last night and saw anyone on the overhead bridge near to junction 6 to contact me as a matter of urgency," said Ch Insp Bland. "Also, anybody who saw anyone hanging around the Dowanfield Road area of Cumbernauld or someone carrying a large white plastic tub last night should get in touch."
A police spokeswoman said no passengers were on the bus when the incident happened.