(CNN) -- Imagine driving down the highway amid the typical stream of cars and trucks to suddenly discover millions of bees swarming toward the morning commute.
A truck flipped on its side Sunday on a highway in Sacramento, California, and let loose its cargo of honey bees.
"There was somewhere between six [million] and 16 million of them running around out there," Officer Steve Merchant of the California Highway Patrol told CNN.
The bees stung cops and firefighters who tried to corral them. They buzzed toward nearby businesses and forced them to shut their doors. They prompted authorities to warn drivers to roll up their windows and turn off their air conditioning -- lest a vent suck in a bee or two.
"People were being stung left and right," Merchant said. "It was an ugly, ugly scene." Watch bees swarm the highway »
The bees escaped from their crates when a big rig carrying more than 400 colonies, or hives, flipped on its side on Highway 99 shortly before 10 a.m.
For the next seven hours, authorities brought in handlers who used smoke to calm the bees and coax them back into their colonies. The colonies were packed in crates that were unloaded from the trailer and reloaded on to other trucks.
Officials do not yet know what caused the truck to turn on its side, but said they think the driver may have been driving too fast.
The load was bound for Yakima, Washington. The bees had likely been used to help pollinate an almond orchard in Sacramento, California, the Sacramento Bee newspaper said.
Honey bees, while always invaluable to farmers for pollination, have become even more precious in recent months because of a nationwide shortage due to "Colony Collapse Disorder," or CCD. Beekeepers throughout the United States have been mysteriously losing thousands of their bees, perplexing scientists, driving honey prices higher and threatening fruit and vegetable production.
In the United States, the honeybee, the world's premier pollinator, experienced a dramatic 40 percent decline, from nearly six million to less than two and a half million, in the last two decades.
In 2005, for the first time in 85 years, the United States was forced to import honeybees in order to meet its pollination demands.
Back in Sacramento, authorities had contained and cleaned up the mess by 5 p.m. They didn't know how many bees remained unaccounted for, but they were getting no calls from panicked motorists.
"In this instance," Merchant said, "no news is good news." E-mail to a friend
CNN's Saeed Ahmed contributed to this report.
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