A spill of frozen bull semen bound for a breeder in the state of Texas triggered a scare that temporarily shut down a US interstate highway during the morning rush hour.
The incident began when the driver of a Greyhound bus carrying the freight alerted the fire department he had lost a part of his load while negotiating the ramp on a highway near Nashville.
"We didn't know what it was, but we were told (the canisters) were non-toxic," said Maggie Lawrence, a fire department spokeswoman.
When firefighters arrived on the ramp, they saw "four small propane-sized canisters (that) began to emit a light vapour," Lawrence said.
In addition to the vapour, the canisters also let off an unpleasant odour and the ramp was closed while emergency personnel tried to determine what was in the containers.
The bus driver turned around to retrieve the canisters. Once emergency personnel learned the smoking canisters were nothing hazardous and that they simply contained frozen bull semen that had been stored on dry ice, Tennessee Department of Transportation and fire department workers cleared the ramp.
"It was no different to us than if a mattress fell off a truck," said transportation spokeswoman BJ Doughty.