The FBI earlier this year tried to obtain records associated with people who accessed an article on USA Today’s website about the killing of two FBI agents as they tried to search a Florida apartment — sparking a legal fight and once again fueling concerns that federal law enforcement is not following its own guidelines when seeking news outlets’ data.

The bureau’s request to Gannett, which owns USA Today, came in late April but spilled into public view only recently after the company resisted it in court.

FBI agents sent the company a subpoena asking for records, including IP addresses and mobile identification information, of those who accessed a Feb. 2 article about the shooting during a 35-minute window that same day.

The subpoena said the demand related to a criminal investigation and asked USA Today not to disclose its existence “indefinitely.” It was unclear, though, precisely what the FBI was investigating or how electronic records pointing to those who accessed the story might advance that inquiry. The subpoena, which did not seem to seek readers’ names, was previously reported by Politico.

In a statement, USA Today publisher Maribel Perez Wadsworth said the organization would fight the demand for the materials.

“Being forced to tell the government who reads what on our websites is a clear violation of the First Amendment,” she said. “The FBI’s subpoena asks for private information about the readers of our journalism. We have asked the court to quash the subpoena to protect the important relationship and trust between USA ­TODAY’s readers and our journalists.”

The shooting occurred when agents went to serve a warrant at a Sunrise, Fla., apartment to which they had linked an IP address suspected of possessing child pornography, people familiar with the matter have said. The man inside, the people have said, opened fire through the door — killing Special Agents Daniel Alfin, 36, and Laura Schwartzenberger, 43 — then took his own life. The bureau has identified the shooter as 55-year-old David Lee Huber and said the agency’s Inspection Division is investigating the matter.

On May 22, Charles D. Tobin, a lawyer with the firm Ballard Spahr who represents Gannett, wrote to the FBI agent who sent the subpoena and objected to turning over the records, asserting that they “fall squarely under the protections of the First Amendment to the U.S. Constitution and the United States Attorney General’s regulations for subpoenas to the news media.”

Tobin noted that Justice Department policies call for law enforcement, in most circumstances, first to notify and negotiate with media members’ whose records they seek, and to get the attorney general’s personal approval. Agents did not appear to have followed the policies, Tobin asserted. On May 28, a day before the deadline the FBI had given the media company to respond to its demand, Gannett asked a judge to quash the subpoena. A ruling on the company’s motion has yet to be issued.

A Justice Department spokesman declined to comment, including on whether the attorney general was notified of the subpoena. An FBI spokeswoman also declined to comment. The subpoena was signed by a supervisory special agent, J. Brooke Donahue, and faxed to Gannett by a different agent, Tracie E. Smith. Reached by phone, both declined to comment.

The Justice Department has in recent weeks disclosed three separate instances in which it secretly sought reporters’ phone records during the Trump administration — for their work at The Washington Post, CNN and the New York Times. The moves drew condemnations from media outlets and First Amendment advocates, who asserted that such tactics could have a chilling effect on reporters’ ability to gather information about the government.

Wadsworth, the USA Today publisher, said the news organization was particularly surprised to have received the subpoena because of Biden’s comments.

“The subpoena is also contrary to the Justice Department’s own guidelines concerning the narrow circumstances in which subpoenas can be issued to the news media,” she said. “Our attorneys attempted to contact the FBI before we moved to fight the subpoena in court and afterward. Despite these attempts, we never received any substantive reply nor any meaningful explanation of the asserted basis for the subpoena.”

It was not immediately clear whether Biden’s comment would cause the FBI to back off its request to USA Today. The moves to seek journalists’ phone records were aimed at identifying sources for news stories, rather than particular readers. Gannett’s lawyers noted that prior court rulings affirm First Amendment protections for readers and publishers alike.

The Justice Department has under both political parties been aggressive about pursuing leak investigations and — at times — seeking journalists’ records to advance that effort. President Barack Obama’s first attorney general, Eric H. Holder Jr., faced significant controversy over collecting the phone records of journalists working for the Associated Press and Fox News. In 2013, Holder issued new, tighter guidelines for how such materials should be obtained.