What's in the Cart?

The article may change as more details are uncovered, but this is the copy I saw.

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LOS ANGELES (Reuters) - Police evacuated a San Diego college arena on Thursday, hours before a first-round NCAA championship basketball game, after a bomb-sniffing dog signaled a potential problem at a hot dog stand.

Cox Arena at San Diego State University was cleared while police tried to determine if there was an explosive device in the hot dog stand, college spokesman Jack Beresford said.

He said it was not immediately clear how many people were inside the building at the time but that the teams had not yet arrived.

"A bomb-sniffing dog noticed something in a hot dog cart," Beresford said. "They got a hit on something that was in the cart itself."
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What was in the cart? A hot dog!? How could that be suspicious? Maybe it was made with tofu.