Firefighters raced to reports of a car fire in Watford this morning after a resident heard a "loud smash" and saw the vehicle begin to smoke.

Hertfordshire Fire and Rescue were called to Whippendell Road at around 6.20am (August 9) to reports of a Black Hyundai on fire.

Police warned drivers to avoid the area after officers were forced to partially close the road near the Hagden Lane junction, causing heavy traffic nearby.

A resident heard a loud smash before loads of smoke came out of a black Hyundai.A resident heard a loud smash before loads of smoke came out of a black Hyundai. (Image: Supplied)

The resident who alerted the emergency services said: “I was up on the balcony just after 6am and then I heard a loud smash that I thought sounded weird. 

“As soon as I looked over the balcony, I saw loads of smoke coming out of the car but it didn’t look like a fire,” the 27-year-old postal worker added. 

“Straight away, I was panicked because it’s not what you’re expecting at 6.20am in the morning and there’s no-one around, so I rang police and the fire brigade."

Firefighters in Whippendell Road this morning.Firefighters in Whippendell Road this morning. (Image: Supplied) She added: “I never saw any flames the whole time I was watching but when I walked down, most of the back window was smashed and the inside of the car looked a bit burnt.”

Photos from the scene show firefighters next to the parked black car with its boot open, which does not appear to be visibly damaged.

The witness claimed that the vehicle's owners - who were reportedly an older couple - looked "really shaken up" when they arrived later while firefighters were still at the scene.

The road closures were lifted by about 7.30am after the car was recovered.The road closures were lifted by about 7.30am after the car was recovered. (Image: Supplied)

A police spokesperson confirmed there were no reported injuries or arrests connected to the incident. An investigation into the cause is ongoing.

Road closures were lifted by around 7.30am after the vehicle was loaded onto a recovery lorry. An employee at Vimco Superstore in Whippendell Road said that the traffic had cleared by 8.20am.

Hertfordshire Fire and Rescue have been contacted for more information.