the news of a downfall of stock prices hit investors, so they obviously
wanted to get rid of their shares.
This is not the way you want to think about prices. Stock prices are determined via the equilibrium of demand and supply. It sounds like you are assuming that they drop from the sky and investors react, but they are determined via the actions of investors. What happens is that news of the fundamentals of the economy (Things like interest rates, employment numbers, job forecasts, etc.) hit, investors react, and then price falls.
Suppose there are two investors A and B and a single stock. Suppose that $t=0$ both investors 'subjectively value' the stock at 10, this valuation is determined via each investors subjective expectations of future earnings and future prices. So the price at $t=0$ is 10 and lets suppose that investor A owns the stock. At $t=1$ news about the fundamentals of the economy hits, each agent updates their subjective value of the stock. Suppose that the 'value' to agent A is 5 and to agent B is 6. Its clear that Agent A will trade the stock to agent B at a price between 5 and 6, hence price falls endogenously not exogenously. As this example illustrates, trade occurs between pessimistic sellers and relatively optimistic buyers.