MOSES LAKE - Authorities are searching for the source of the bomb threat that forced an evacuation of the Grant County International Airport Thursday morning.

About 8:45 a.m. Thursday, an airport employee received a call of a bomb in the terminal. About 50 people were evacuated from the building as a precaution, according to Greg Becken, manager of security and information technology for the Port of Moses Lake.

Deputies found nothing suspicious during a walk-through of the building, according to the sheriff's office.

Potter, a bomb-sniffing dog from the Grand Coulee Police Department, searched the terminal. Officer Sean Cook said Potter did not find any threats inside.

Big Bend Community College and area businesses remained on lockdown until about 11:30 a.m.

Kyle Foreman, of the Grant County Sheriff's Office, said investigators are tracking the source of the phone call. Foreman said in the past, investigators have worked with phone companies to track the location of calls, a tactic that has been successful in other incidents.

Potter is the only dog in Grant County law enforcement trained to sniff out chemical compounds used in explosives. Cook said the dog is trained to respond to thousands of chemical compounds used in explosive devices. He added Potter has been with the department for about eight years.

Emergency plans were in place for the airport, as well as the college and nearby Columbia Basin Job Corps.

Air traffic was uninterrupted by the bomb threat, Foreman said.