We use simple past (there was) to describe the past, and present perfect (there has been) to describe the present... rather obviously. ;) The second sentence is incorrect in both examples, so perhaps this rewrite will clarify the difference: "There was an accident. I hope no one was hurt." (You also need to tell us when the accident happened.) "There has been an accident. I hope no one is hurt."

In this context both forms produce a very similar meaning. So I think you can use both. However. Was -> usually used when something happened at some time in the past. It could have been an hour ago, a day ago, centuries ago, a billion years ago, but it wasn't just now. Has been -> usually used when something happened just now. So in this case you can think the first statement as something happened in the past but not just now.

there was = past tense there has been = present tense The same rules apply as always.