A gang of robbers armed with pick axes and a running chain smashed their way into a jewellers, a court heard.
Terrified Owner Nasir Hussain was told to get down by one of the masked intruders when they raided his Carlton Street store.
The four masked men stole an estimated £150,000 worth of gems on April 14 last year.
WS Jewellers, off Westgate, was one of three bespoke stores targeted by the thieves, Leeds Crown Court was told heard.
Mr Hussain said he was working alone at about 4pm on the day of the Grand National when he heard the sound of breaking glass.
The gang smashed their way through a window and one told Mr Hussain to ‘get down’
Mr Hussain said: “Then I saw two or three men start smashing virtually everything where the counters are.
“At the point I could see a large bag, a sack, in the middle of the shop. They were emptying those counters and throwing those trays of jewellery into that sack.”
A raider also demanded to know where the safe was and took about £4,000 of cash and some more jewellery.
Mr Hussain said: “I saw one person outside with a chainsaw, a running chain saw and he was waving that chain saw, virtually holding it up high.”
The court has also heard how the chain saw was used to frighten off anyone who thought about intervening.
The gang then left through the window and made their getaway in a Mitsubishi people carrier.
Mr Hussain said: “I was just shocked and terrified. At the time I didn’t know what to do. I felt as if it’s not right. So I basically came out of the same window and I just jumped into my own car.”
He caught up with the robbers near Horbury Road, close to the bottom of Westgate End.
Mr Hussain said: “I just turned the car around and blocked the road. They ran straight into me.”
The court heard the robbers reversed back and drove off. They then swapped cars at Westgate Common WMC on Park Grove Road and set off again in an Audi, which was later found burnt out close to the Coopers Arms in Birstall.
The gang are alleged to have transferred to a third vehicle, another Mitsubishi.
But a witness managed to take down the registration and this led to a string of arrests.
Standing trial are John Boy Morrison, 40, of Cottingley Spring caravan site, Gildersome, Patrick Lowther, 33, of Castle Lodge Gardens, Rothwell, Steven Barker, 35, of Merchant Court, East Bowling, Bradford, and Garner Smith, 33, of Montrose Street, Bolton Woods, Bradford.
They all deny conspiracy to rob.
The trial continues.