Multiple Agents Editing Single Ticket

We have multiple agents who need to be able to take individual ownership of tickets before working them. I am running into an issue where multiple agents open the same ticket and assign themselves to it. This is leading to duplication of work because both think they are the only one working the ticket.

My previous support system would alert subsequent agents that the ticket was already assigned when they tried to assign it.

Any ideas on how to make sure the first agent to assign locks out others or at least creates warning for them?

Thanks