Forensic scientists and officers from the homicide unit were due to examine the scene.
F1 teams and drivers have expressed their shock at the news of her death.
Spaniard Fernando Alonso, the Ferrari driver, said: "Today is a very sad day for Spanish sport. We have lost a fighter with a huge smile."
Britain's Jenson Button added: "It's horrendous news. Very tragic, the girl has been through so much, more than most people go through in their lives. It has been tough for her but this is horrific news and a real shock to the whole paddock and the world of motorsport.
Tributes are paid to Maria De Villota following the F1 reserve driver's death in Spain
"We saw her this year in Barcelona. We were doing some work for a children's charity and she was the first one to put her hand up to do it, and got a lot of other drivers involved - she was doing a lot for the community."
Sauber team principal Monisha Kaltenborn, who worked alongside De Villota as an ambassador for the
Women in Motorsport commission,
BBC Radio 5 live:
"I had so much respect for the courage she had and how she fought against all the odds and I'll always remember her having a smile, no matter what happened.
"After the accident everybody else would have thought she doesn't really want to have anything to do with motorsport.
"But no - there she was, texting away and saying she wants to be back as soon as possible.
"It didn't take her any time at all until she was back; she was planning maybe even to drive but more important to her was to give other people the courage that you can still do so much even if you've had such a major setback."
Tom BurridgeBBC News, Madrid
"Maria De Villota was not only admired for competing near the very top of a male-dominated sport, but also for the way she had recovered from her terrible accident in the summer of 2012.
"Here in Spain she was known for her strength of character and positive spirit, and the charity work she did away from the track, promoting road safety and campaigning against domestic abuse.
"Next week her autobiography, entitled 'Life is a Gift' was due to be published, and only a few weeks ago she was interviewed on Spanish TV. She talked enthusiastically about her life, and the challenges that lay ahead."
De Villota spoke movingly
about the initial recovery stages following her accident and recalled: "The surgeon came up to me with my family around him and said: 'Maria, we have saved your life, I don't know if you remember you had a serious accident but we have to tell you that you have lost your eye'.
"I asked him: 'Are you a surgeon? Do you need both hands to operate? I am a Formula 1 driver and I need both eyes to drive.
"Before, I only saw F1, I saw myself in a car competing. I did not see what was important in life, the clarity to say: 'I am alive'.
"It has given me my bearings, given me back what's important. I accept it with the energy to say I am going to live out this chance 100%."
Martin Whitmarsh, the McLaren team boss and president of the Formula 1 Teams' Association (Fota), said F1 would discuss what would be the appropriate way to mark De Villota's death over the Japanese Grand Prix weekend but that it was not a simple decision.
"We will be talking amongst ourselves," he said told BBC Sport. "You have to be careful; a lot of racers don't want these issues to detract from a race weekend.
"Everyone wants to demonstrate the right level of sympathy but the real racers would want the show to go on and wouldn't want a fuss to be made. It's not something we need to amplify, it's something we've got to be sensitive about."
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