A SECURITY guard was threatened with a knife after challenging two thieves at Tesco's Hill Street store in Blackburn.

The two youths were attempting to leave without paying for a bottle of vodka when the guard confronted them. They escaped after one of them produced the knife.

Both were white, aged between 17 and 19 years.

One was 5ft 9 ins, with shoulder length, greasy, dark brown hair parted in the middle. He was wearing a cream coloured Kangol jacket and baggy, cream combat trousers.

The second had similar hair and was wearing a black three-quarter length jacket and blue baggy trousers.