NEW YORK (AP) -- Defense stocks tumbled Tuesday, dragged down by fears of a weakening global economy that sent the Dow Jones Industrial Average down by more than 3 percent.

The defense sector selloff afflicted Bethesda, Md.-based Lockheed Martin Corp., Los Angeles-based Northrop Grumman Corp., Falls Church, Va.-based General Dynamics Corp. and Providence, R.I.-based Textron Inc.

U.S. stock markets headed lower after a 9 percent slide in Chinese stocks, with the Dow briefly falling by more than 500 points before rebounding somewhat later in the day. The last time the Dow dropped more than 500 points was on Sept. 11, 2001.

Lockheed gained 4 cents to $97.61 in aftermarket trading, after dropping $3.55, or 3.5 percent, to close at $97.57 on the New York Stock Exchange. Shares traded between $69.87 to $103.50 over the last 52-week period.

Shares of Northrop gained 13 cents to $72.04 in aftermarket trading, after dropping $1.93, or 2.6 percent, to $71.91. Shares traded between $61.51 to $75.72 over the last 52-week period.

Textron shares gained 8 cents to $90.91 in aftermarket trading, after dipping $4.33, or 4.5 percent, to close at $90.83 on the Exchange. Shares traded between $80.46 to $98.96 over the last 52-week period.

Shares of General Dynamics dropped $2.76, or 3.5 percent, to close at $75.33 on the NYSE. The company traded between $61.20 and $81.28 over the last 52-week period.