A fire which broke out at a building planned to house migrants in eastern Germany was greeted with cheers from some onlookers, police say.
The fire in the town of Bautzen in the early hours of Sunday morning destroyed the roof of a former hotel, which was being converted into a migrant shelter.
Police said some of the crowd tried to prevent firefighters from extinguishing the blaze, which destroyed the roof.
The premier of Saxony, Stanislaw Tillich, described them as "criminals".
Police suspect arson. The investigation includes detectives who normally deal with extremist crimes. No-one was hurt.
Only a few days ago, protesters in another Saxon town, Clausnitz, blocked the arrival of a bus taking migrants to accommodation.
They shouted, "We are the people", the slogan of the 1989 peaceful uprising which led to the fall of the Berlin Wall and the reunification of Germany.
The director of the Clausnitz migrant shelter is a member of the anti-immigrant Alternativ fuer Deutschland (AfD) party.
Police in Bautzen said many in the crowd watched the fire and commented with "unashamed delight". Two drunken men were arrested after they refused to leave the scene.
The converted hotel was supposed to house 300 migrants.
In a further sign of anti-migrant sentiment, police in the Brandenburg region are investigating the distribution of leaflets urging "absolute resistance" against "foreigner invasion".
The leaflets, put through letterboxes in the town of Nauen, are the suspected work of neo-Nazis. They also give instructions on making firebombs and using explosives.
On Saturday, police defended their response to events in Clausnitz after two videos surfaced online.
The first video showed 100 hostile demonstrators preventing a bus from off-loading migrants into their accommodation on Thursday.
A second appeared to show police roughly manhandling a boy from the bus into the building.
The regional police chief said there were too few police to keep the protesters away, and three of those inside the bus had provoked the crowd.
Germany received over a million asylum claims in 2015 and has been widely admired for opening its doors.
But with that have come increasing reports of anti-migrant incidents amid fears of a backlash, correspondents say.
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.