Letters containing a “toxic” white powder were sent to at least three official buildings in Brussels, the Belgian capital’s royal prosecutor announced on Friday evening, saying no one was injured, AFP reported.

These envelopes arrived on Thursday at the State Guard, the office of the Minister of Justice and the court, the prosecutor’s press release says.

“All people who came into contact with the powder are isolated and examined. No one was injured,” the prosecutor clarified.

“The white powder found in the letters contains the toxic substance Brucin (…), dangerous only when consumed by humans,” the press release states. “Skin contact is not dangerous.”

The prosecutor assured that “the first results of the investigation showed that these facts are not related to the shootings of recent days in Brussels” related to the drug trade.