MADRID (REUTERS) - The Spanish government will send convoys carrying the Covid-19 vaccine and food supplies on Sunday (Jan 10) to areas cut off by Storm Filomena which brought the heaviest snowfall in decades across central Spain and killed four people.

In the Madrid area, rescuers reached 1,500 people trapped in cars, while police broke up a large snowball fight after the authorities appealed for citizens to stay at home for risk of accidents or spreading the coronavirus.

Forecasters warned of dangerous conditions in the coming days, with temperatures expected to fall to up to minus 10 deg C next week and the prospect of snow turning to ice and damaged trees falling.

In Madrid, police cordoned off buildings with heavy loads of snow on the roof in case of accidents, but residents took to the streets in droves to enjoy the rare sight of their city blanketed in white.

About 100 workers and shoppers have spent two nights sleeping at a shopping centre in Majadahonda, a town north of Madrid, after they were trapped by the blizzard on Friday.

"There are people sleeping on the ground on cardboard," Mr Ivan Alcala, a restaurant worker, told TVE television.

Madrid's main international airport was closed and the operator said it would not reopen until Sunday afternoon at the earliest, when flights would resume gradually.

About 20,000km of roads across central Spain were affected by the storm, and the government would send convoys transporting the vaccine and food supplies to those in need, transport minister Jose Luis Abalos said on Saturday.

A 36-year-old woman gave birth in an ambulance in Madrid on Saturday after health workers were unable to get her to hospital.

One man and a woman in a car drowned after a river burst near Malaga in the south, while two homeless people froze to death in Madrid and Calatayud in the east, officials said.

The State Metereological Agency said up to 20cm to 30cm of snow fell in Madrid on Saturday, the most since 1971.