Investigators are being very careful as they look into who left an explosive device outside the police department of a Colorado mountain town.
The Boulder County Sheriff's Office in Boulder was temporarily shut down Thursday morning after someone stepped forward to offer information about the case. FBI spokeswoman Deborah Sherman says the person's vehicle was swept and the office closed as a precaution.
No threats were found, but she wouldn't comment on whether the person offered anything useful to the investigation.
A police detective in the town of Nederland, about 15 miles southwest of Boulder, found the device in a bag when he began his shift Tuesday morning.
The FBI says it was active but failed to detonate.