The New York Stock Exchange temporarily halted trading in all securities at 11:32 a.m., New York time, Wednesday morning. No explanation was immediately provided by the NYSE's parent company, Intercontinental Exchange Inc.

All open orders would be canceled, an alert on the exchange's website stated. It continued, "Additional information will follow as soon as possible."

nyse Announcement on the NYSE website. Photo: NYSE

Art Cashin, director of floor operations at the NYSE, told CNBC, "We had some technical problems even before the opening." 

Such a widespread glitch is extremely rare on the stock exchange. Previously, technical difficulties have affected only parts of the NYSE. 

Last year, technical bugs afflicted stock quotes and prices on the NYSE for a half-hour, but did not affect wider trading of securities. 

Before trading slammed to a halt, the Dow Jones had been down more than 200 points as anxiety over the ongoing Shanghai market crash worried investors. 

THIS STORY IS STILL DEVELOPING. MORE INFORMATION TO COME.