The 45-year-old man is under police guard at Lismore Base Hospital following a lengthy police operation nearby at Wollongbar, in the Northern Rivers region, on November 23.

Assistant commissioner of the northern region Peter McKenna said police were called to a property on Bruxner Highway about 8am because of a "concern for welfare".

He said police negotiators worked with the occupant, who was alone at the property, to resolve the incident "without any issues whatsoever".

The police operation finished about 2pm.

"[A] man was taken into police custody safely with no injuries to anyone, which was really pleasing to see," Mr McKenna said.

"The man is being assessed at the moment at Lismore Base Hospital."

He did not confirm if the man had firearms or explosives, or if he was previously known to police, and he had "no information" about any significant crimes committed by the man.

"Police are searching the property at the moment," Mr McKenna said.

An exclusion zone was set up around the property to keep the community safe and was not uncommon in these situations, he said.

And the man did not enter Wollongbar TAFE - or leave the Bruxner Hwy property - at any time.

"I'd like to say the public were instrumental in assisting us with that operation, in listening to police and being guided by the police in the area," Mr McKenna said.

The Wollongbar TAFE campus spent hours under a lockdown while the police operation unfolded.

A bus arrived at the campus about 1pm to take students to Alstonville Showgrounds, while some students were leaving on foot.

Student Xavier Lasselle told reporters the emergency siren for a lockdown went off about 9am.

"At first we didn't think much about it... thought it was a practice run or something like it normally is," he said.

"About half an hour later we saw the PolAir circling the TAFE."

He was in a classroom with the doors locked and blinds down for "a couple hours", before police came around at 12.30pm to tell the students they were being evacuated.

The Bruxner Hwy remains closed in both directions between McLeans Ridges Rd and Sneaths Rd in Wollongbar with motorists being diverted.

According to Live Traffic NSW the highway has been closed since 9.10am.

At 11.30am, Richmond Police District said the incident was isolated to a private property on the Bruxner Hwy.

Officers were at the scene with assistance from the police helicopter, police negotiators and the Tactical Operations Unit.

A TAFE NSW spokesperson earlier said the lockdown was a precaution and nothing was happening on the campus itself.

A message was heard playing over loudspeakers at the campus saying, "attention, attention. An emergency exists. Please follow the lockdown procedures".

NSW Police said the Bruxner Hwy at Wollongbar is expected to remain closed for some time and don't have an estimated time for reopening.

The best way for people to stay updated is by visiting www.livetraffic.com as this should be updated soon after the road reopens.