In the gospels, Luke refers to 'the women while Mark specifies Mary M, James mother Mary, and Salome, and John recounts the event according to Mary M, but all agree they 'found' the stone rolled away. I can't imagine anyone would let an open tomb supposedly newly occupied after instruction to be seal go unreported for too long, especially if guards are posted after its sealing. However, Matthew 28; recounts Mary M and 'the other' Mary having witnessed the rolling away of the stone with the guards thereafter fainting before (waking up, i assume, and) going to report the event... With that said, Sunday's dawn, 6a.m.ish is not considered part of any Sabbath day... unless it happens to coincide with a high holy day or it has since been ordained because of that particular occurrence.