Eleven family planning centers around the state, including one in New Haven, received letters Thursday containing a white powder and note saying that powder was anthrax, state and federal officials said.

“We responded to a huge amount of such incidents today, revolving around family planning facilities,” said Lisa Bull, an FBI spokeswoman.

Field tests showed no sign of anthrax, officials said.

The letters, with identical return addresses, were sent via FedEx to clinics in Hartford, Bridgeport, Danbury, Meriden, Wallingford, New London, Norwalk and New Haven.

Tonya Little, a manager at the Summit Medical Center in Hartford, told WVIT-TV that she opened the letter and powder spilled out. She said she set the letter down and called authorities.

“Someone is planning carefully and trying to scare us,” she said.

The clinics were closed while authorities investigated, and workers showered.

FedEx Corp. issued a statement Thursday the company is working with law enforcement to determine who sent the letters.

“The safety and security of our customers and employees has always been a top priority at FedEx,” the company said. “FedEx is aware of receiving some suspicious letters for delivery to a few locations and is taking immediate action, including full cooperation with law enforcement authorities and their investigation, and close communication with affected organizations and Fed Ex employees.”

Brian Emanuelson, an emergency response coordinator with the state Department of Environmental Protection, said further testing would be done on the powder.

“We are taking all the precautions, because these were intended to be a threat to scare people and we want to make sure this not what they say it is,” he said.

–Associated Press