SUNNYSIDE, Wash. -- Sunnyside police have one man in custody in connection with a bomb threat at a downtown bank Thursday, but authorities are keeping most details of the incident under wraps.

The incident began at 11:40 a.m., when employees of the Bank of America on Seventh Street called 9-1-1 to report a bomb threat they received by phone, police Chief Ed Radder said.

Arriving officers found employees evacuating the building, while one remained inside talking to a man who walked in at the same time as the call, Radder said.

Police took the 38-year-old Sunnyside man into custody, said Radder, who called him a "person of interest" but not a suspect.

It was unclear what the caller or the man wanted, the chief said.

Police had planned to question employees and witnesses into Thursday evening with the help of an FBI agent, he added.

FBI agents typically assist in bank-related investigations because banks are insured by the federal government, said Special Agent Frederick Gutt, an FBI spokesman from Seattle.

He knew no details about the Sunnyside incident.

Police ask those with information about the incident to call 509-836-6200.