Bee experts believe that the 12 million disgruntled bees strapped in crates to the back of an overturned tractor trailer on a New Brunswick highway should be contained by nightfall Monday.

The crash happened early Monday morning when the trailer's load shifted, causing the truck to roll over on the Trans-Canada highway near St. Leonard, N.B.

The bees were contained in 330 crates -- some of which broke open from the force of the impact.

The scene was uneventful after the accident as it was raining and cloudy and the bees were staying close to the hives. But they were becoming more and more agitated when the weather became sunnier in the afternoon, RCMP Sgt. Derek Strong told CTV Newsnet.

"We were happy up until now but now it's not as good as it was this morning," Strong said at about 1 p.m. ET.

"Bees don't fly in the rain of course, they stay put. So the rain was helping us. The sun came out a short time ago and it's warming up. The heat is not helping things at all so we have a fire truck there spraying down the load trying to keep the bees calm and cool."

A Department of Natural Resources fire truck was brought on scene to spray the bees down, to keep them in their hives.

Originally, the RCMP only closed one westbound lane. But as onlookers flocked to the area, police decided to close all four lanes of the highway.

"There are quite a few bee stings happening up there at the highway," Strong said.

"In an unfortunate incident a journalist who was trying to get some bee noises on her microphone suffered a dozen or more stings. All in the name of journalism I guess, but it's best to stay away from that area. Twelve million bees can do a lot of damage."

The RCMP is advising motorists in the area not to get out of their vehicles, and to keep driving. CTV Atlantic's Erin O'Halloran said officers were following their own advice.

"The RCMP aren't outfitted for this type of operation, so they're staying in their cruisers, their lights are on, and they're not getting out," she said Monday afternoon.

Emergency personnel, including paramedics and ambulances were on standby, just in case.

Strong said the undamaged hives are being moved to a new trailer.

The remaining hives will be moved at dusk, when the agriculture workers expect the bees to return to their hives.

Paul Vautor, president of the New Brunswick Beekeepers Association, said while bee stings could be quite dangerous for those with allergies. People were told to stay 200 metres or further from the site of the accident, where there shouldn't be any concern.

"The bees will be busy defending their hives ... making sure no intruders come in. They'll also be some bees flying around the close vicinity that have become disoriented if they can't distinguish their own hives. So they'll be trying to reorient themselves.

"They could be a little bit defensive and be prepared to sting."

Vautor said trucks hauling bees are common this time of year. The trucks were being transported back to Ontario on Monday after being used to pollinate a blueberry crop in northeast New Brunswick.

"About the first week of June, wild blueberry crops come into blossom. Because we don't have enough bees in New Brunswick, we have a shortage of honey bees," Vautor told CTV Newsnet.

"We have about 9,000 colonies here and about 10,000 or 12,000 colonies are imported from outside the province to pollinate the wild blueberry crops."

The accident was the first of its kind in New Brunswick.