Councillor Karen Davies, a governor at the school, has told Wales Online she believes the incident was a stabbing and that two members of staff were injured.
“I have no confirmation on how serious the injuries are,” she says.
Earlier, Dyfed-Powys Police said three people were injured in the incident.
Davies says she doesn’t know whether any children were injured.
“I send my thoughts to those injured and all the people there. I know how well the school rehearsed lockdown and I am sure everything is under control.”
“It is shocking. You hear about these things happening in Manchester and London but it is literally our comprehensive here.”