Register and unregister a handler while iterating throught the vector of handlers

I have got a very small program which starts a thread and dispatches events to the registered set of handlers. Handlers class look as follows.

class Handler
{
public:
    /* OnEvent must return void. This is part of the user interface agreement */
    virtual void OnEvent(struct Event*) = 0;
    virtual ~Handler();
};

Handlers are kept inside the vector

std::vector<Handler*> handlers;

I can add a handler to the vector using register function and delete a handler from the vector using unregister function. Handlers can either be added or removed within the OnEvent function.

Prototypes are below

void registerHandler(Handler *h);
void unregisterHandler(Handler *h);

Thread function looks as follows. It will block on event and once event is received it will dispatch this event to every handler which is in the vector

void thread_function()
{
    struct Event* e = getEvent();


    /* Function will receive an event and will invoke handlers one by one */
    for(auto s = 0; s < handlers.size(); ++s)
    {
        /* Register and unregister function can be called inside OnEvent. */
        handlers[s]->OnEvent();
    }
}

What would be the most optimal way to add and remove a handler from the vector inside OnEvent function?

My idea was. When register is called inside OnEvent I will push back a handler to the handlers list. But I cant think of any way how to remove handler from the vector. If I remove a handler from the vector the iterators will not be valid anymore. Will be very interesting to hear your thoughts, guys.

Thank you