Three cars were severely damaged in a suspected arson attack.

Firefighters were called to Sandown Road in Watford yesterday at 3.09pm after receiving a call that a blue Citroen was on fire.

Eyewitness Dave Carter was driving home when he saw the smoke.

The 51-year-old said: "At first I thought it was a huge bonfire or something, the smoke was billowing over the top of the houses. 

"As I passed Sandown Road I could see the fire brigade were there and at that point were trying to smash the windscreen to put the fire out inside. 

"I heard a small explosion, which could have been a tyre or the engine maybe."

Hertfordshire Fire and Rescue Service said one car was ablaze and two other cars were affected by smoke and heat damage. 

Initial investigations have been carried out and there are no further lines of enquiry at this stage.