Write a question about the following article: The 1994 Monaco Grand Prix was a Formula One motor race held on 15 May 1994 at the Circuit de Monaco, Monte Carlo. It was the fourth race of the 1994 Formula One season, and the first following the deaths of Ayrton Senna and Roland Ratzenberger at the San Marino Grand Prix two weeks previously. The 78-lap race was won by Michael Schumacher driving a Benetton-Ford, his fourth victory from the first four races of 1994. Martin Brundle finished second in a McLaren-Peugeot, with Gerhard Berger third in a Ferrari.
Who died at the San Marino Grand Prix two weeks previously?