Yes, this is true. And many people also suffered losses in it. Same happened with me. I kept my amount in an exchange and they stopped withdrawing it for quite some time. It has been more than 6 months. I am not able to withdraw my coins. Seeing all this, I feel that it is not safe to keep your funds in any exchange.
Which exchange are you talking about? Is it an Indian exchange or and international exchange? If you can share more details then we might be able to create more awareness and ask fellow community members to not use that exchange.