New Orleans Pelicans center Jaxson Hayes -- the #8 overall pick in the 2019 NBA Draft -- was arrested after an alleged violent altercation with police, TMZ Sports has learned ... and it apparently got so extreme, the hooper and a cop were taken to a hospital.

We're told law enforcement were called to an LA area home for a domestic disturbance early Wednesday morning ... and when cops attempted to check on the parties involved, 21-year-old Hayes tried like hell to keep them from entering the premises.

Sources tell us 6'11", 220-lb. Hayes got combative with cops and a fight broke out ... with the ex-Texas Longhorns star getting tased in the middle of the scuffle.

The brawl was allegedly so intense, police put out an "officer needs help" radio call.

Hayes was taken to a nearby hospital to get treatment for minor injuries ... and an officer involved in the fight also sought treatment, although their condition is unknown.

Hayes is expected to be booked for felony battery on a police officer. Cops are still investigating the initial alleged domestic incident, but both parties have been uncooperative.

We've reached out to Hayes' rep. So far, no word back.