Watford town centre is gridlocked after a set of traffic lights failed outside Tesco Extra.

Witnesses say it is impossible to leave the Waterfields retail park at the moment.

Emergency services are on scene redirecting traffic.

Giles Cooper, spokesman for Hertfordshire Constabulary, said: "We were called at 11.50am with reports that the traffic lights as you leave Tesco on Lower High Street have failed.

"Highways are aware and en route.

"Traffic is building up significantly. Officers are en route to assist with redirecting traffic at the moment."