A Humpty Doo school went into lockdown Monday morning after a 35-year-old man with a crossbow allegedly made threats against the school, NT Police said.

Police were notified that the man was allegedly threatening the secondary school on Challoner Court around 7:50am, forcing the school into lockdown.

The man was found by police in his vehicle on Challoner Street where he was arrested.

A crossbow that was found in the vehicle during the arrest was seized, police said.

The 35-year-old man is known to the school, but police did not say if he was staff, a parent or connected in another way. He remains in police custody while investigations continue.

“Police urge anyone with information about the incident to make contact on 131 444,” police media director Mark Wilton said.

“Please quote reference number P25331519. Anonymous reports can be made through Crime Stoppers on 1800 333 000 or via https://crimestoppersnt.com.au/.”