Detectives today warned that violent armed robbers, who are targeting Bradford bakery bosses, are very dangerous.

The masked gang, who have struck five times, have used increasing levels of violence and attacked women and lone workers in a series of targeted raids.

In the latest incident, shortly before 6pm on Monday, a bakery worker at the Crusty Pie Company in Stanage Lane, Shelf, was hit with a hammer, threatened with a knife and had bleach thrown in his face.

The 35-year-old was tied up and held by two of the robbers while the third forced the safe and stole a substantial amount of cash. The employee was treated at Bradford Royal Infirmary.

In July and December last year the company's owner was attacked by the three-man gang while at home, in Thornton, Bradford, with his partner and children.

In the first raid the men, brandishing bars and sticks, forced their way in, threatened the couple and stole jewellery and a car. On Christmas Eve they broke in and, armed with a large knife and wheel brace, demanded cash and jewellery. But after a scuffle they fled empty-handed.

Minutes later they turned up at The Stone Chair Variety Club, in Ing Head Terrace, Shelf, went into the upstairs living quarters and demanded cash from the stewardess's partner.

He was held hostage while the stewardess was forced to open the safe. The gang escaped, with a large amount of cash in a dark-coloured Mazda 6 car.

The fourth raid happened on January 12 at the home in Lightcliffe, near Shelf, of the owners of another Bradford pie bakery, Stobart's of Low Moor.

The three robbers, armed with crowbars, smashed the conservatory window and demanded cash, before picking up knives from the house and forcing the women to hand over the jewellery they were wearing and the men their watches.

A scuffle developed and the bakery owner was hit over the head with a crowbar. He was detained overnight in hospital.

Detectives are looking into the background of the owners and staff at the Crusty Pie Company for any clues as to why they have been targeted three times.

Detective Inspector Ash Hewitt, of Calderdale CID, said: "We will be looking at whether someone may have had inside knowledge or the premises were targeted because of a belief that they had substantial amounts of cash there.

"The two bakery companies know of each other but there is no association between them."

Det Insp Hewitt added: "These are extremely dangerous men. The level of violence used on each occasion has increased, they have used violence and force against females and have been very targeted in their victims.

"The concern is how far the aggression and violence will go until they are caught. They clearly do not care what they do. They could have blinded the baker by throwing bleach in his eyes."

One of the suspects is believed to be 17 or 18 and another is in his early 20s and police believe they are likely to brag about their exploits. The suspects are believed to be white. Two are about 5ft 10ins tall and the third is about 5ft 6ins.

Anyone with information is asked to call CID on (01422) 337085, or Crimestoppers, anonymously, on 0800 555111.