Halifax Regional Fire and Emergency's use of drones to scope out unknown substances inside a transport truck today is proof the new tools are invaluable, says a municipal spokesperson.

Highway 102 between the Kearney Lake Road and Larry Uteck Boulevard exits was closed to traffic early this evening as emergency crews investigated a truck that was pulled over on the shoulder.

"It's the potentially most dangerous situation in which we've had to use the drones since they've been put into service earlier this year," said Brendan Elliott. "What it does is it actually potentially saves the life of a first responder."

Halifax Regional Police said the driver of the truck was having a medical emergency and was taken to hospital.

Police are still investigating whether the contents of this transport truck are dangerous. (CBC)

Elliott said two drones were brought in to get a closer look while first responders watched aerial video from about 50 metres away.

He said the drones — which he called "an extension of first responders' eyes" — could be used to go inside the truck and transmit details, including any names of potentially dangerous substances.

"They're both there substituting what even just a year ago would have had to have been haz-mat firefighters potentially putting their lives at risk to determine the same thing that we're finding out today without risking anyone's life," said Elliott.

Highway reopens

Two lanes of Highway 102 are now open, and one lane remained closed as the scene was cleared.

Police said in an email that the substance is still unknown, but it doesn't appear to be suspicious and is being processed as a precaution.

Haz-mat crews remove objects from a truck that was pulled over on the side of Highway 102 on Thursday. (Nic Meloney/CBC)

Elliott said until first responders know it's safe, they treat any unknown substance as dangerous.

"We don't know yet how dangerous or not dangerous it is, and the drones thankfully are going to be able to shed a tremendous amount of light on that for us," he said.

'First major incident'

The department bought two unmanned aerial vehicles last year, after the municipality approved a $60,000 pilot project.

They cost about $3,000 each and come with a thermal-imaging camera that identifies hot spots, from people lost in a wooded area to a wildfire burning underground.

Emergency crews were on the scene of Highway 102 between the Kearney Lake Road and Larry Uteck Boulevard exits. (CBC)

Firefighters started using the drones in March, and so far, they've only seen action a handful of times, including to search for missing people.

Elliott said today's incident shows how valuable they can be.

"This is one of the first major incidents in which we are sacrificing potentially a drone where in the past, we were putting firefighters' lives in danger," he said.