Shanghai shares closed down nearly six percent Friday, extending their plunges of recent weeks as analysts said panic was setting in.

The benchmark Shanghai Composite Index slumped 5.77 percent, or 225.85 points, to 3,686.92 on turnover of 648.1 billion yuan ($106.0 billion). The index lost 12.07 percent over the week.

The Shenzhen Composite Index, which tracks stocks on China’s second exchange, plummeted 5.30 percent, or 117.33 points, to 2,098.48 on turnover of 505.1 billion yuan. It lost 16.16 percent in the week.