Ambulance crews are lucky to be alive after a brick was thrown at their windscreen.

The 999 crew had just picked up a patient with heart problems from Harpenden and were heading up the M1 towards the Luton and Dunstable Hospital when the thugs struck.

The ambulance was travelling between junctions 10 and 11 on the northbound carriageway of the M1 at around 7.30pm on June 8 when the object was thrown off a bridge.

Ambulance service spokesman Gary Sanderson said: “This is a despicable act to carry out. This mindless act could have seriously injured or even killed our crew and the patient and other road users on the motorway. Words cannot describe how the crew felt following this incident. The crew, both men, and the patient were very shaken up indeed. They were able to carry on their journey to the hospital.”

Two youths wearing hoods were seen running away from the bridge after the brick was thrown. Anyone who witnessed or has any information about this incident is asked to contact police as soon as possible.

The ambulance was taken off the road to have the damaged windscreen replaced.