AUSTIN—Video footage shows a suspect standing in front of the Governor’s Mansion, igniting an object and throwing it onto the porch of the historic landmark setting off a blaze that ravaged the 152-year old structure, investigators said Thursday.

“We’re here to confirm that we do have an arson crime that has been committed at the Governor’s Mansion,” said State Fire Marshal Paul Maldonado. “The video is still being enhanced ... we’re still reviewing, studying and analyzing the video.”

Maldonado said the cameras did not capture the suspect leaving the mansion’s front yard and he did not know if other people may have been present at the time.

“What we saw was that the fire progressed very rapidly and the reason it progressed is because there was an accelerant involved,” he said.

The mansion grounds were surrounded by an 8-foot chain-link fence and Department of Public Safety troopers were on guard.

Speaking at the state Republican convention in Houston, Gov. Rick Perry paused to pay homage to his residence for eight years.