NEW YORK (Reuters) - Fears about the economy and unrest in Saudi Arabia darkened the outlook for equities Thursday, pushing major indexes below key technical levels.

The Dow Jones industrial average was down 228.48 points, or 1.87 percent, to end unofficially at 11,984.61. The Standard & Poor's 500 Index was down 24.91 points, or 1.89 percent, to finish unofficially at 1,295.11. The Nasdaq Composite Index was down 50.70 points, or 1.84 percent, to close unofficially at 2,701.02.

The Dow's worst day in seven months came after reports that authorities in Saudi Arabia had opened fire on demonstrators, increasing anxiety about instability in major oil-producing nations. (Reporting by Angela Moon; Editing by Jan Paschal)