One man, 52, was heading north on the M1 near Ourimbah on Monday afternoon when he felt something hit his head, causing him to lose control of his car briefly.

He turned and saw a passenger leaning out of a passing truck firing shots from a nail gun at his SUV, causing his passenger-side window to shatter, police were told.

The incident came minutes after another driver, 57, was shot with a nail gun in the right arm near Somersby.

Both victims reported seeing a white Mitsubishi truck pass by when hit by the nails.

The truck was found in a commuter car park about 10 minutes later by police.

A 19-year-old man who ran from the car park was pepper-sprayed and arrested by officers.

He was charged with seven counts including armed with intent to commit an indictable offence, assault occasioning actual bodily harm in company and being subject of an outstanding warrant.

He was remanded in custody ahead of an appearance in Wyong Local Court on Tuesday.