NEW YORK (Reuters) - Wall Street shares plunged on Monday as investors fled technology stocks amid resurgent trade war worries, with key indexes trading below their 200-day moving averages and the S&P 500 closing below that pivotal technical level for the first time since Britain's vote to leave the European Union in June 2016.

The first trading day of the second quarter began with a broad selloff concentrated in the technology and consumer discretionary sectors, as losses by Amazon.com (AMZN.O), Tesla (TSLA.O) and Microsoft (MSFT.O), among others, took center stage from retaliatory trade measures China unveiled on Sunday.

"It’s more complicated than just a tech selloff. What's hurting everything is that the S&P went through its 200-day moving average," said Brian Battle, director of trading at Performance Trust Capital Partners in Chicago. "That attracts momentum sellers and they don't care what the fundamentals are."

The Dow Jones Industrial Average (.DJI) fell 458.92 points, or 1.9 percent, to 23,644.19 after dipping below its 200-day moving average. The S&P 500 (.SPX) fell 58.99 points, or 2.23 percent, to 2,581.88 and the Nasdaq Composite (.IXIC) dropped 193.33 points, or 2.74 percent, to 6,870.12.

Amazon.com (AMZN.O) was the biggest drag on the S&P 500, down 5.2 percent, as President Donald Trump continued his twitter attacks on the online retailer.

All 11 major sectors of the S&P 500 closed lower, with the biggest losses seen by the consumer discretionary (.SPLRCD) and technology (.SPLRCT) indexes, which were down 2.8 percent and 2.5 percent, respectively.

U.S. Treasury yields fell to two-month lows as investors fled sliding stocks for safety ahead of Friday's closely watched jobs report.

Declining issues outnumbered advancing ones on the NYSE by a 4.17-to-1 ratio; on Nasdaq, a 4.14-to-1 ratio favored decliners.