Why is the San Marino Grand Prix 1994 called F1's 'Black Weekend'?

The San Marino Grand Prix 1994, often called F1's 'Black Weekend', was the sport's deadliest race weekend. It saw the deaths of Roland Ratzenberger on Saturday and three-time world champion Ayrton Senna on Sunday. Ratzenberger died during final qualifying, while Senna passed away after a Lap 7 crash during the race. Rubens Barrichello was seriously injured in a separate incident.