Matthew Poole and continuators on Mark 16:8

8 And they went out quickly, and fled from the sepulchre; for they trembled, and were amazed: neither said they any thing to any man; for they were afraid.

Both Luke and Iohn mention two Angels in the habit of young Men, Matthew speaks of one sitting upon the Stone. They might see him sitting upon the Stone, and yet find him within also, the motions of Angels are quick, and indiscernable to our sense, or the Stone might be rolled inward. That they were affrighted is no wonder, considering how apt we are to be affrighted by any apparitions. Concerning what the Angel said to these women, read the Notes on Matth. 28.7.8. They presently fly from the Sepulchre amazed, saying nothing to any, till they came into the City, where they tell it to the Disciples.