The damage done to the etched glass on one of the front doors of Iolani Palace by a vandal Saturday morning is "irreparable," a palace official said.

A woman, accompanied by a man, walked up the front steps of the palace at about 8 a.m. Saturday and kicked the door, cracking the glass of one of two left-side doors as they made their way into the historic building, said Kippen de Alba Chu, palace executive director.

The glass cracked "pretty badly," but a special tint treatment placed on the glass to prevent damage from vandalism and strong wind stopped most of the glass from actually shattering, de Alba Chu said. "Some small pieces ended up on the carpet."

The glass, which depicts the image of a Hawaiian woman, was ordered in England and etched in San Francisco in time for the opening of the palace in 1882, de Alba Chu said. The palace was built by King David Kala­kaua as the official residence of the Hawaiian monarchy and is a designated National Historic Landmark.

"We are devastated that one of our original etched glass doors has been destroyed," de Alba Chu said Sunday. "It is an irreparable loss of a treasure."

A footprint made by the woman could be seen on the damaged glass, he said. "We can get a new one made, but it won’t be the original."

A 30-year-old man, who listed no address, and a 21-year-old Hawaii Kai woman were arrested by police on suspicion of criminal property damage shortly after 8 a.m. They have not been charged, and were later released pending investigation, according to Hono­lulu Police Department records.

The couple actually entered the Great Hall of the palace for a moment but, after the alarms to the building sounded, fled outside, where they were caught by three palace guards, de Alba Chu said.

"The force of the kick actually caused the door-locking mechanism to the door to open because it was an original lock as well," he said. The opened door then slammed into a large and historically significant Chinese vase but did not damage it, he said.

"It was gifted to Kala­kaua by Chinese merchants upon his coronation," he said.

Palace staff will work with HPD to ensure the case is prosecuted, he said.

"This is very serious," de Alba Chu said. "They could have harmed other artifacts inside the Grand Hall."

A similar act of vandalism that occurred more than a decade ago may have prevented more serious damage. Someone threw a rock and smashed in the glass at one of the central front doors of the front entrance in the 1990s, de Alba Chu said. Those doors were replaced by stronger, anti-vandalism glass doors, and on Saturday security video showed the woman unsuccessfully trying to kick in the those doors first before kicking one of the two left-side doors. When the two central doors were replaced in the 1990s, palace officials also had the four other front doors reinforced, he said.

At one point during the incident, de Alba Chu said, the woman shouted, "This is my house!"

"Our guards looked at them, her eyes were pretty glassy, so we think they were pretty high," de Alba Chu said. There was no indication either was trying to make a political statement.

"The husband wanted to fight" but did not make any moves to do so against the three palace security guards, which included "two of the biggest ones" on staff, de Alba Chu said. After being apprehended, the couple sat on the front steps as police arrived.

Both suspects have prior convictions for petty misdemeanors, according to court documents. The two told security guards they are married, de Alba Chu said.

The palace staff was getting ready for its regular 9 a.m. opening and the guards were inside when the incident began, de Alba Chu said.

The front doors are rarely opened and only for ceremonial purposes, he said. The most recent time was when the Dalai Lama visited in April 2012.

De Alba Chu said palace officials are not considering more drastic preventive measures, such as installing wrought-iron bars on the glass windows.

Not only would that be against historical-building rules, but also would be "the last thing we would want to do."

Queen Liliuokalani, following the 1893 overthrow of the monarchy, was imprisoned at the palace for eight months in 1895, from Jan. 16 to Sept. 6.