The widow of Orlando nightclub gunman Omar Mateen was arrested Monday by the Federal Bureau of Investigation and charged in connection with the attack that left 49 dead, according to law enforcement officials.

Noor Salman faces charges of obstruction of justice and of aiding her husband’s attempt to provide material support to the Islamic State militant group, a spokeswoman for the U.S. attorney’s office for the Middle District of Florida said.

She is expected to appear in federal court on Tuesday morning in Oakland, according to the U.S. attorney’s office in San Francisco. The charges will include accusations that she aided her husband and had some foreknowledge he planned to carry out an attack, the official said.

She was arrested by the FBI in the Bay Area, where she grew up and where her family lives, according to an FBI official.

Ms. Salman’s attorney and family members could not be immediately reached for comment Monday.