Onlookers celebrated as a suspected arson fire damaged a former hotel being converted into a refugee home in eastern Germany, police said Sunday, raising new concerns about violence toward new arrivals in a nation that registered more than a million asylum-seekers last year.

The blaze in the roof of the building in Bautzen, in the eastern state of Saxony, broke out overnight. Police said no one was injured but a group of people gathered outside, some "commenting with derogatory remarks or unashamed joy" at the fire.

While most Germans have been welcoming toward refugees, a vocal minority has staged protests in front of refugee homes, especially in the east. Germany last year saw a surge in violence against such lodgings.

Police ordered three people to leave the fire scene because they were hampering firefighters' work and then temporarily detained two of them, whom they described as intoxicated 20-year-old locals, after they ignored the order.

Investigators found traces of a fire accelerant at the scene and believe the fire was caused by arson, police said. It wasn't immediately clear whether the building can be restored.

Saxony is home to the anti-Islam and anti-immigration group PEGIDA, and incidents there have caused concern before. In August, a mob in Heidenau, outside Dresden, hurled bottles and fireworks at police protecting a shelter being set up for refugees.

The Bautzen fire came after a mob in the small town of Clausnitz, also in Saxony, on Thursday screamed "We are the people!" and "Go home!" as they blocked a bus carrying asylum-seekers outside a new refugee home.

Police drew criticism in that case for roughly hauling some refugees off the bus into the building — which they insist was necessary to prevent the situation from escalating — and for saying that some of the refugees had made provocative gestures.

Saxony Governor Stanislaw Tillich called the two incidents "appalling and shocking" and described the perpetrators as "criminals."

"This is abhorrent and disgusting," Tillich told the Funke newspaper group. He pledged that authorities will investigate and "bring everyone responsible to account."

Interior Minister Thomas de Maiziere said that everyone in Germany is entitled to express their concerns "but there is a threshold of decency and law that must not be crossed — and this threshold was clearly crossed in the incidents in Saxony," the news agency dpa reported.

"It is completely unacceptable for people who are seeking protection from persecution here to be greeted with hatred and agitation," de Maiziere added.

Later Sunday, the minister defended police actions in Clausnitz, saying they were right to get all the refugees off the bus quickly and into the building. If the bus had been backed away from the refugee home, "these bawling people would have had their way," de Maiziere said on ARD television.