Two immigrants raised alarm among local Missouri residents after buying 59 prepaid cell phones in a single shopping trip at a Wal-Mart, prompting the FBI to get involved.

Ultimately, the agency concluded there was no terrorism threat, but said it was important to remain vigilant and that bulk cell phone purchases in the past had been signs of terrorist activity, according to a Yahoo News report.

In addition, employees of a store in Columbia saw someone buy 50 cell phones, prompting them to call the police. Reports continued to roll in, and five cities had reported unusually large sales of prepaid cell phones. Combined with reports of propane tank theft in Kansas City, it seemed like a recipe for a terrorist plot.

The FBI looked into the claims out of “an abundance of caution,” FBI spokeswoman Bridget Patton said according to the report. However, authorities ultimately determined there was no terrorism link. Sometimes, people try to pull a profit by buying up a bunch of cell phones and then selling them.

The reason why prepaid cell phones are so suspicious is that they are popular among people who don’t want to be tracked. They are called burners because they can be used and thrown away without any identifying information that would allow police to track down the user.

But they’re also useful for legitimate purposes to immigrants or the poor who can’t afford to buy a smartphone and sign up for a cell phone plan but need a way to stay in contact with people.

Of course, people have been buying burners for many years now, and no one has batted an eye to the practice. The fact that more reports are being made to police of prepaid cell phone purchases indicates how skittish much of the public is when it comes to terrorism. A recent Gallup poll indicated that 49 percent of Americans were very or somewhat worried that they or someone they know would become victim to a terrorist attack.