DUBAI, July 8 (Reuters) - Egypt's stock market fell sharply in the opening minutes of trade on Monday after state media reported that dozens were killed in violence at the Cairo headquarters of the Republican Guard.

The main index was down 2.5 percent. It surged 7.3 percent last Thursday after the ouster of president Mohamed Mursi raised hopes for the installation of a technocratic government that could address economic problems, but has dropped back since then.

Egyptian state television said the death toll in an attempt to storm the Republican Guard headquarters had risen to 42. It said an additional 322 people had been wounded.

The shootings appeared to deepen Egypt's political crisis; the Muslim Brotherhood accused security forces of attacking peaceful protesters at the headquarters and called on Egyptians to conduct an uprising.