Holding Indian passport, travelling from US-HK-India, can I visit Shenzhen for 2 days?

I am travelling from Bangalore -HK-SFO and SFO-HK-Bangalore, and would like to stay over in HK for 2 days and visit Shenzhen for 2 days to meet our suppliers, can use 72 hr free transit?
is there any other ways to get quick visa since I do not have much time, otherwise I have to make another trip. thanks.