Nova Scotia's police watchdog was looking to speak with witnesses Tuesday after gunfire erupted during an early morning traffic stop on Highway 101, sending the driver of the vehicle fleeing into the woods.

The vehicle was pulled over by RCMP on the exit 15 on-ramp around 4 a.m., but few details have been released regarding what happened next.

The Serious Incident Response Team will only say that an "incident" took place between the police officer and the driver while the vehicle was stopped and a firearm was discharged.

The driver fled on foot into nearby woods.

A 26-year-old man was later found by police and taken to hospital for treatment of a non-life-threatening injury. He remains in police custody, said SIRT.

Traffic was backed up on Highway 101 following the incident. (Paul Palmeter/CBC)

RCMP say the man is expected to appear in Kentville provincial court. They have not said what charges are being laid.

They have also not disclosed who fired the weapon, nor have they said if the man or a 20-year-old passenger who remained in the vehicle and was arrested are known to police.

The police officer involved in the incident called for backup but was not injured, said RCMP.

Police shut down Highway 101 between exits 15 and 16. Emergency response teams, police dogs and a helicopter were used in the search for the driver.

The RCMP forensic identification team was on the scene on Highway 101. (Paul Palmeter/CBC)

The closure of the highway snarled traffic during the commuter rush hour, and the road was expected to be closed for most of the day. Vehicles were rerouted to Highway 1.

RCMP also advised Somerset and District Elementary School to cancel classes for the day.

One resident of Parker Condon Road, which runs parallel to Highway 101 in the Berwick area, told CBC News she got a call from RCMP telling her to lock her doors at around 5:30 a.m. She said she hadn't heard an update from RCMP since then, and felt nervous and upset.

<a href="https://twitter.com/hashtag/RCMPNS?src=hash&ref_src=twsrc%5Etfw">#RCMPNS</a> There is no risk to the public regarding the situation near Hwy 101 between Exits 15 and 16 —@RCMPNS

SIRT was contacted by RCMP just before 7 a.m. and has investigators on the ground.

"The situation is still very fluid," SIRT director Felix Cacchione said in an interview shortly before noon.

"It arose from a motor vehicle stop. What happened from there, I'm not sure."

SIRT is looking to speak with witnesses. Investigators can be reached at 1-855-450-2010.