Police in Derbyshire are stepping up their inquiries into attacks in which bricks or other objects have been thrown at vehicles.

The investigation follows an incident early on Sunday morning when a paramedic was seriously injured when a brick was thrown at his ambulance.

He is in hospital suffering from serious head injuries after his ambulance veered off the road and crashed.

A male crew member and a friend of the patient were slightly injured in the crash.

Spot checks

The police, who have set up an incident room in Belper with 20 officers, said there may have been more than 20 similar attacks in the last month.

Police records of damage to cars along the A52, A515 and A517 into Ashbourne are being re-examined.

Police spokesman John Briggs said they now believe the acts may have been deliberate.

"It is a disturbing trend. We believe that somebody in a moving vehicle is throwing something at other vehicles," he said.

High profile patrols have been introduced along the three roads and spot checks are being carried out.

The results of forensic tests into a brick recovered from the scene of the ambulance accident have not yet been released.