Why was referee Mark Smith suddenly carried out of the T Mobile Arena during the UFC 324 event?

UFC referee Mark Smith was carried out of the T-Mobile Arena after suffering an ACL injury at UFC 324, Dana White confirmed. Smith was hurt after officiating Ateba Gautier vs Andrey Pulyaev. The night also saw Paddy Pimblett taken to hospital after losing to Justin Gaethje, who won the interim lightweight title.

Why was referee Mark Smith suddenly carried out of the T Mobile Arena during the UFC 324 event?
UFC referee Mark Smith was carried out of the T-Mobile Arena after suffering an ACL injury at UFC 324, Dana White confirmed. Smith was hurt after officiating Ateba Gautier vs Andrey Pulyaev. The night also saw Paddy Pimblett taken to hospital after losing to Justin Gaethje, who won the interim lightweight title.