The Spanish government will send convoys carrying the COVID-19 vaccine and food supplies on Sunday 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 authorities appealed for citizens to stay at home for risk of accidents or spreading COVID-19.

Forecasters warned of dangerous conditions in the coming days, with temperatures expected to fall to up to minus 10 Celsius (14 Fahrenheit) 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 center 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," Ivan Alcala, a restaurant worker, told TVE television.

Madrid's international airport suspended flights until Sunday night.

About 20,000 km (12427.42 miles) 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.

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 Meteorological Agency (Aemet) said up to 20-30 cm (7-8 inches) of snow fell in Madrid on Saturday, the most since 1971.