Boston City Councilor Tania Fernandes Anderson broke her silence a day after news broke that she was the subject of a federal investigation, vowing to stay in office and “show up and fight” for her constituents.

Federal authorities are investigating Fernandes Anderson and have sent subpoenas to City Hall, according to two people with knowledge of the probe.

A Boston city councilor is the subject of a federal investigation, reports say, but it is not yet clear what the topic of the investigation is. District 7 Councilor Tania Fernandes Anderson is under investigation,

Boston City Councilor Tania Fernandes Anderson is under federal investigation, a source familiar with the matter told 25 Investigates. Details about the probe were not immediately available on Tuesday. No criminal charges have been filed. Boston 25 has reached out to Fernandes Anderson for comment.

In response to a public records request about Fernandes Anderson, a City Hall official sent a letter that quotes the U.S. Attorney's Office, saying, "the integrity of a grand jury investigation would be impaired by disclosure of the information sought," adding that the investigation is at a "very critical juncture."

The exact focus of the probe isn't known, and no criminal charges have been filed. The council's president said Tuesday it was important to respect the legal process and "drawing any conclusions right now would be premature.

Fernandes Anderson took remedial actions, but was warned that referral to the Attorney General is on the table if further instances of noncompliance are found.

A Boston city councilor reportedly subject to a federal investigation declined to comment on the matter in a statement Wednesday, but thanked her supporters and committed to staying in office. “My job is show up and to fight for you.

The nature and circumstances of the probe were not immediately known, and no criminal charges have been filed at this time, according to two people with knowledge of the requests.