“Look!” The Greek word is idou (#2400 ἰδού), and it is used to get our attention. See commentary on Matthew 1:20 (“Look!).
“some of the guard.” At the same time that the women were traveling to tell the disciples, some of the guards arrived at Jerusalem and gave their report to the Jews. The Bible does not say how many guards watched the tomb, but only “some” of the guards reported what they saw, the rest were apparently so terrified they ran off and stayed hidden.
The religious leaders bribed the guards with a large amount of money to say the disciples stole the body while they were asleep, a report that is still often believed. Also, the Jews told the guards that if Pilate heard they had fallen asleep, a capital offense, the Jews would take care of that also. That fact confirms that the guards were Roman soldiers and not Temple police, because if Jewish police had fallen asleep on the job and the body of Jesus been stolen, Pilate would have not cared at all about it. But if Roman soldiers on duty had fallen asleep and botched their assignment, they could have been executed.
God sent an angel to roll back the stone in sight of the guards (Matt. 28:2-4). This was grace upon grace to them. He did not have to do that. He could have just rolled the stone back by invisible power. God gave the guards a wonderful opportunity to believe in, and testify to, the resurrection of Jesus Christ. It was not something they expected when they got “tomb guard duty,” but it is what happened. We never know when God is going to move powerfully in the world. If we happen to be fortunate enough to be part of a move of God, we need to be prepared to believe and testify. These guards showed that they were more interested in money than the truth.