LOS ANGELES, United States (AFP) — A truck crash that set 250 million bees free has sparked warnings in the western United States, with police telling people to avoid swarms of the stinging insects.

The accident happened in Washington state in the far northwest of the country, when a semi trailer carrying a load of hives overturned.

“250 million bees are now loose,” wrote Whatcom County Sheriff on its social media page.

“AVOID THE AREA due to the potential of bee escaping and swarming.”

Roads in the region, which nestles the border with Canada and is just 30 miles from Vancouver, have been closed as bee experts help with the clean-up.

While some beekeepers aim only to produce honey, many others rent out their hives to farmers who need the insects to pollinate their crops.