A 'huge explosion' has caused a power outage in the centre of Beverley on Saturday night. Witnesses reported hearing the explosion just after 9pm, with electricity in a number of shops and bars suddenly cut off. Northern Powergrid have confirmed engineers are on site to their substation in Toll Gavel to investigate the explosion, with nearly 160 properties affected. Power is expected to be back online by 11.30pm. One person told the Mail the explosion caused residents to spill out onto the streets. "I'm at Walkergate. Heard a huge explosion which scared the crap out of me," she said. "It was so loud it brought everybody out onto street and set alarms off. "Spoke to police who said officers were attending an incident in Saturday market." The explosion caused shop alarms to go off, with people reporting cinema screens in nearby Flemingate Centre switching off. Witnesses have said it has not caused any visible damage. Another witness said: "I witnessed the bang in the town centre. It was a very loud bang. "All the shops burglar alarms went off, quite scary! Turns out it's an electrical sub main has blown near Toll Gavel church. "Spoke to national power grid and an engineer is on their way to look at the problem." A Northern Powergrid said engineers would be working to fix the problem. Northern Powergrid have confirmed they are investigating reports of a "explosion". A spokesperson said: "We have had a report of an explosion at one of our substations in Toll Gavel. Engineers are en route to investigate what the cause is at the moment. "We have got about 159 properties without an electricity supply. "It is a potential explosion but we need to get there first and find out what it's about."