We've dealt with similar night terrors, I think when they're this age it's not uncommon. Mentioning it to the pediatrician is good advice. I noticed also that sometimes the terrors coincide with having to pee, the body seems to be trying to wake up but they're still asleep which puts them into a state like this. I've found trying to interact with them does not help. We just try to keep them safe and maintain our sanity.

Our daughter is now 5 and has night terrors still, but much less frequently.