What is the best way to let a user know that another user is working on the same item?

At my company we have an admin tool, where users can create and edit surveys.

But we have a few problems with users working on the same items which in a lot of cases has lead to data getting lost or corrupted because someone else save stuff.

Is there a good way to let users know that someone else is currently working on a specific item?

Solutions I have thought of:

• Showing a info box with a warning letting the user know someone else is currently editing this item.
• Preventing a user from working on item that is currently being worked on.