Ambulance bosses were forced to activate a major-incident plan after hundreds of trips, slips, and falls as yesterday morning’s black ice sparked an “unprecedented” number of 999 calls.

And accident and emergency units in the Bradford district reported experiencing a massive increase in injuries, with Airedale Hospital near Keighley dealing with four times as many patients as usual and Bradford Royal Infirmary seeing a “high demand” for its services in the hazardous weather.

Yorkshire Ambulance Service (YAS) enlisted its non-essential patient transport service to cope with a surge in demand to treat patients injured in a number of traffic collisions across the city, as well as people hurt after slipping on icy roads and pavements.

Dr Alison Walker, executive medical director for YAS, said last night: “The service has received hundreds of 999 calls for weather-related incidents and we are treating a lot of patients involved in road traffic collisions and injured in slips, trips and falls.

“These calls are in addition to other medical emergencies such as heart attacks and strokes.”

Airedale A&E consultant Meg Crossley said many people had been “caught out” – injuring themselves in slips, trips and falls – because it did not look icy outside.

“The forecast for the weekend is for the weather to be warmer, but if it happens again the message we would like to put out is for people to think before they head out and ask themselves if their journey is really necessary,” she said.

A Bradford Teaching Hospitals spokesman said Bradford Royal Infirmary’s emergency department had also experienced high demand for its services due to the “hazardous icy conditions” throughout the city.

“We have seen a huge increase in weather-related injuries from slips, trips and falls, as well as an increase in fractures.

“We are making every effort to treat patients as quickly as possible but would urge people who don’t have an obvious life-threatening illness or injury to consider accessing advice and treatment from non-emergency organisations such as NHS Direct, the local pharmacist or GP surgery, or by visiting a local walk-in centre.

“We are urging people to take care and only come to BRI’s A&E department if it is a medical emergency.”

The Met Office said warmer weather was expected today Police warned commuters to take extreme care while travelling after an “exceptionally high amount” of collisions caused by fog and ice in the early hours of yesterday – including accidents on both carriageways of the M62 and the M606. Chief Insp Derek Hughes, of West Yorkshire Police’s road policing unit, said: “It was treacherous. Drivers should be aware of the conditions and drive accordingly.”

A number of schools across the district were forced to close yesterday, or opened later than planned, because of fears over black ice and slippery routes for parents, children and staff.

Schools fully closed included Feversham College, Ingrow Primary, Long Lee Primary, Killinghall Primary, Riddlesden St Mary’s CE Primary, Saltaire Primary, Holy Family and All Saints’ CE Primary. All are expected to reopen on Monday.

Bradford Council said its gritters had been out all morning responding to reports of ice and would patrol the district from 8pm yesterday in case temperatures drop again.

Grit bins can be requested by calling (01274) 431000 but resources are said to be “severely limited”.