Detectives believe a gang who staged a terrifying and brutal raid on a Bradford jewellers may have been 'casing' the business for days.

Witnesses spotted a group of men hanging around outside Zeb Jewellers in Heaton on several occasions before robbers stole thousands of pounds-worth of gold in an early-morning attack.

The 24-year-old owner and his wife were woken at 4.30am on Saturday by three masked men - one brandishing a gun - who had forced their way into their home in Springcliffe Street.

The proprietor of the jewellers was beaten around the head with a metal bar or hammer before being forced to let the robbers into his adjacent store in Heaton Road.

The men - who are all thought to be Asian - took gold worth tens of thousands of pounds.

Detective Constable Paul Harrison of Bradford North Police said: "On a number of days prior to the robbery a group of Asian men were seen in the area paying particular attention to the shop."

Witnesses had spotted them hanging around outside, looking suspicious, on Monday, Tuesday, Wednesday and Friday, said Det Con Harrison.

"We believe they are not from the immediate vicinity as local people did not recognise them," he added.

He said there had been three or four Asian men in their 20s, at least one of them with a beard.

Detectives described the robbery - which left the victim with serious heads wound and his wife in shock - as ''a terrifying attack on two respected people".

The owner was treated with stitches at Bradford Royal Infirmary but was later released.

Det Con Harrison said: "These are well-thought-of people in the area and residents are doing what they can to help."

Police appealed for anyone who may have been in the area at the time - such as late-night taxi drivers - to contact them with any information.

They are not linking the raid to a robbery on an Asian jewellery salesman in Westgate, Bradford, on Wednesday.

Anyone with information about this crime should contact Bradford North CID on (01274) 376059.