Forgpt about Alesi and Montermini accidents.
The cars were ridicoulsly fast with very little protection for the drivers. Crashes and injuries were almost bound to happen.
Coppied this off of the Wikipedia site about F1 1994:
Technical changes
In order to combat the spiralling costs of running a Formula One team, and to counteract criticism that over-reliance on technology was reducing the drivers to a secondary role, sweeping rule changes were introduced for 1994, most notably banning of all electronic "driver aids" such as active suspension, anti-lock brakes, traction control and launch control.
Ayrton Senna was among several observers who said that, with such features removed but no attempt to curtail the speed of the cars, 1994 would be "a season with a lot of accidents".
1994 also saw the reintroduction of refuelling during the race for the first time since 1983, and after Ayrton Senna's crash at Imola a 10mm wooden plank was affixed to the underside of every car to prevent ground-effect advantages. Wear was permitted on the plank up to 1mm by the end of the race. In addition, after Imola several further rule changes were made involving reducing the effectiveness of the airbox (by creating holes in it) and creating dorsal support for the head of drivers in the cockpit.