BEIJING, March 23 (Xinhua) -- The benchmark Shanghai Composite Index plunged over 4 percent in the afternoon session on Friday following the U.S. decision to hike tariffs on China's steel and aluminum imports.

As of 2:00 p.m. Friday, the Shanghai Composite Index plunged 4.02 percent and the smaller Shenzhen index dived 5.16 percent.

A total of 170 stocks dropped by the daily limit of 10 percent on the two bourses and over 1,000 stocks sank over 7 percent during the afternoon session.