An irate Santa Claus astonished children at a Christmas event in St Ives, Cambridgeshire, this week when he burst out of his grotto during a fire evacuation to shout and swear at them while tearing off his hat and beard.

The entertainer is understood to have told attendees to “get the fuck out” after a smoke machine at a family-friendly rave in the same building as his grotto set off a fire alarm.

Organisers of the event have apologised for “any offence or distress” caused by his behaviour.

The incident took place on Sunday in the town’s Corn Exchange building at an event organised by Festival Event St Ives (FESt), a local non-profit group. It was advertised as a chance to see Santa and his “chief snowman” in the buildup to Christmas and was run separately to the rave.

Santa saw red after the smoke alarm went off. As families were hastily told to evacuate the area, onlookers said he began to behave “very strangely”.

He is reported to having ripped off his costume and started swearing at the crowd of about 50 children. DJ Stuart Wilkin said Santa was “raging” as he encouraged the children, who were already on their way out, to evacuate.

He added: “I do think though the reason Santa was raging was because they booked a kids’ rave on the same day as kids going to see Santa upstairs above the event.

“He probably sat there trying to talk to kids with thumping music playing and was pissed-off. The fire alarm going off was probably the final straw for him.”

One observer, Adam Gaynor, said on social media: “The guy dressed as Santa at the Corn Exchange is an absolute disgrace.

“He came charging in, ripped his hat and beard off in front of 50 odd kids and started shouting and swearing at people to leave.”

One mother told Cambridgeshire Live that Santa used “the most vile language, ripping off his hat and beard with steam literally coming from his ears”. “I’m not too sure why he was so cross?” she added.

That question remains unanswered. The woman said one of her friend’s children became extremely distressed when “Santa told them to get the fuck out”.

FESt later apologised for the incident. A statement on its website read: “FESt wish to apologise for any offence or distress caused to parents and children by the attempts to ensure all visitors and staff had exited the building and were safe.”

The mother interviewed told Cambridgeshire Live that she had to tell her children he wasn’t the “real Santa. He was an imposter and will be going on the naughty list”.