Federal authorities are investigating a fire early Sunday that damaged the entryway to the headquarters of the Republican Party of New Mexico in Albuquerque.

Agents working with local authorities recovered unspecified “incendiary materials” at the scene, said Bureau of Alcohol Tobacco, Firearms and Explosives spokesperson Cody Monday. He declined to say what the materials were or to share further details.

The fire follows numerous acts of vandalism in recent weeks directed against Tesla, the electric-car company whose owner, Elon Musk, has led Republican President Donald Trump’s effort to slash the federal workforce. Several of those cases involved Molotov cocktails that were used to start fires at dealerships. U.S. Attorney General Pam Bondi has called it a “wave of domestic terrorism.”

Attacks on property carrying the logo of Elon Musk’s electric-car company are cropping up across the U.S. and overseas. While no injuries have been reported, Tesla showrooms, vehicle lots, charging stations and privately owned cars have been targeted.

Firefighters responded to the fire just before 6 a.m. and brought it under control within about five minutes, according to Lt. Jason Fejer with Albuquerque Fire Rescue.

The building was unoccupied and no one was injured. But the blaze badly burned the entrance and caused extensive smoke damage throughout the office, where three people work full time, according to Fejer and Republican party representatives.

A photo provided by GOP representatives showed the charred entrance of the building with wood and pieces of burned insulation scattered on the ground. A broken and burned door was set to one side.

The GOP office’s security system detected the fire, said New Mexico Republican Party Chair Amy Barela. She credited firefighters with quickly extinguishing the flames and preventing the fire from spreading.

Albuquerque Mayor Tim Keller called arson a cowardly act.

“Politically motivated crimes of any kind are unacceptable, and I am grateful to our fire department for their swift response," the mayor, a Democrat, said in a statement Sunday afternoon. "This incident is being investigated at the federal level, and I urge anyone with information to report it immediately.”

Barela said GOP representatives also found spray paint on the side of the building about 50 feet (15 meters) from the entrance, saying “ICE=KKK.” Monday, the ATF spokesperson, declined to comment on the graffiti.

Agents from the FBI also were on the scene investigating, according to Fejer. FBI representatives could not be reached immediately for comment.