Federal officials say the gunman accused of fatally shooting an Indiana police officer threw a Molotov cocktail at an FBI field office before the deadly encounter.

The criminal complaint released Thursday by the U.S. attorney’s office in Indianapolis charges 44-year-old Shane Meehan with premeditated murder of a federal agent.

The complaint gives no possible motive for the Wednesday afternoon attack outside the FBI office in Terre Haute that killed Terre Haute police Detective Greg Ferency, a 30-year department veteran who had been a federal task force officer since 2010.