A man in his 20s was rushed to hospital after collapsing while on a tour of Belfast city centre on a 15-seat bike.
The man fell ill in the Amelia Street area of the city about 6.15pm yesterday.
Jennifer Kenna, co-director of the Wee Toast Tours company which runs the bike tours, said members of her staff went into a nearby hotel for a defibrillator and two nurses working nearby came to give first aid.
“We understand he had an underlying heart condition,” Ms Kenna said.
The passenger signed a waiver saying he was fit to cycle, but he did not take any alcohol and was planning to start work at 7pm, she added.
“We are praying for him to make a full recovery. We have around 1,000 passengers a week.”
All her staff are CPR trained and the company meets all city council safety requirements, she added.
Police and the Ambulance Service said they were called to a report that a man had fallen from a vehicle or bike.
An ambulance took him to the Royal Victoria Hospital where it is understood he was still being treated last night.