Staff and Wire Reports

NORMAN, Okla. -- A Chase bank branch in Norman and two in Oklahoma City received letters Monday claiming to contain a substance that could kill whoever opened the envelopes.

"Erring on the side of caution, they called us and similarly erring on the side of caution, we're treating it as if it was in fact some hazardous material involved," Norman Capt. Leonard Judy said.

FBI spokesman Gary Johnson said at least some of the letters did contain a substance, but an initial examination appeared to indicate it is not dangerous

Further testing is planned.

Johnson says similar letters destined for other Chase branches in the area were intercepted before they were opened.

He says the letters said the threat was "based on past actions of the bank."

At least 10 employees of the Norman bank were decontaminated but Johnson says he doesn't know if employees at the other banks were decontaminated.

No dangerous substance was immediately found at the scene, officers said.

Five other banks in Denver, Colo. were also targeted by the threatening letters.