Anti-smuggling units of Istanbul police cracked down on a gang of organ smugglers and arrested four, security sources said Friday.

Acting on a tip that the gang used forged documents to transplant organs in four private hospitals in Istanbul, police raided several addresses on April 9, detaining nine suspects.

Four among them were arrested, while five others were released pending trial. Media outlets said the gang bought organs from poor people for small sums, sold them to wealthy patients awaiting transplants for a large amounts of cash and collected millions of Turkish liras in illegal sales.