At least 30 letters containing suspicious powder have been mailed to Chase banks in nine cities but so far appear to be harmless, authorities said Tuesday.
The FBI said it was investigating "a series of letters sent to banks around the country."
"These threat letters contain a powder substance," the FBI said in a statement. "At this point, field tests on the powder have been negative. Additional testing will be completed. Even sending a hoax letter is a serious crime."
A law enforcement official said the letters were mailed to Chase bank branches in or near Atlanta; Chicago; Columbus, Ohio; Dallas; Denver; Newark, N.J.; New York City; Oklahoma City; and Washington.
The letters all appear to be from the same source and were sent from Texas, the official said. They began showing up at the banks on Monday, according to the official who spoke on condition of anonymity because he was not authorized to discuss the matter publicly.
A city official in suburban Chicago, where two letters showed up at a Chase credit card processing center, said they were mailed from Amarillo, Texas.
The U.S. Postal Service and state and local officials are also investigating. Postal inspector JoJan Henderson says the letters appear to be related.
No injuries were reported. JP Morgan Chase & Co. spokeswoman Mary Jane Rogers says some employees, including a pregnant woman, were examined as a precaution.
Neither the local Postal Service nor the FBI has released the text of the letters or their origin.
Branches 'on alert'
Eight banks in the Denver area and eight in the Oklahoma City area received letters containing white powder, officials there said. All Denver branches reopened Tuesday.
In Oklahoma, the state Department of Health is conducting tests on the substance found in the notes, but Gary Johnson, an FBI spokesman there, said preliminary assessments done locally determined it to be harmless calcium.
Johnson said the Oklahoma letters indicated that the threat was "based on past actions of the bank" and that the letters implied that the opener was going to die.
Nine branches in New Jersey and a credit card center in Elgin, Ill., also received similar threatening letters, said Greg Hassell, a JP Morgan Chase spokesman in Houston. The Chase credit card processing center in Elgin is about 30 miles northwest of Chicago.
Hassell said authorities were in the process of clearing those locations, and some of those nine New Jersey branches were still closed as of Tuesday afternoon.
All the suspicious mail that has been tested has turned out to be harmless, Hassell said, but other Chase branches around the country "are on alert."
Susan Olafson, public information officer for the city of Elgin, said the facility there received two letters, one Monday night and one Tuesday. She said both letters were mailed from Amarillo.