KEY WEST, Fla. -

Key West police locked down the post off on Whitehead Street Friday after someone found a "threatening letter" with a white substance inside the package.

The city's hazardous materials team responded about 12:47 p.m. and the people inside went through a decontamination process.

Several people were taken to Lower Keys Medical Center as an added precaution.

The post office didn't reopen Friday.

The FBI is investigating.