Toddler nightmares?

I have a 2.5 year old who, in the past week or two, a few times has woken up between 10-12 at night crying hard. Same block of time. I assume it's a nightmare. He's crying hard, shaking, pointing at the crib sometimes very tense. He is quite the talker but during those times, he will not tell me what happened at all. So I'm assuming it's a nightmare. He'll cry for maybe 5 minutes the whole time while I'm holding and caressing him, give him a drink of water, and lay him back down to bed.

Do you think it's nightmares? Is it normal? Have you gone through this? It's almost like the same exact time on the nights it happens!! Thanks.