Teachers have reported nearly 2,500 “negative incidents” of bigotry and harassment at U.S. schools in the first 10 days since Donald Trump’s election as president.

More than 10,000 teachers and other educators responded to an online survey administered by the Southern Poverty Law Center’s Teaching Tolerance project, and 90 percent of respondents said the election had negatively impacted students’ behavior and mood.

Eight in 10 respondents said they were anxious and concerned for their students, especially black, Muslim and LGBT children and teens, and they were worried how Trump’s election would affect themselves and their families.

The teachers reported a noticeable increase in verbal harassment, the use of slurs and other derogatory language, and incidents involving swastikas, Nazi salutes and Confederate imagery.

Many of the incidents involved students taunting classmates with variations on Trump’s campaign rhetoric, such as threats to build a wall around or deport Latino students.

Even the minority of teachers who hadn’t noticed any change in student relationships since the election admitted they worked in schools with few minority students or immigrants.

“The takeaway message is first of all that school administrators and school board members and anyone who has to do with education has a crisis on their hands,” said Maureen Costello, director of Teaching Tolerance.

“If you’re talking about at least a quarter of students — and it’s estimated that a quarter of students in American schools are immigrants, or the children of immigrants — suffering trauma, that is going to have quite the impact over the course of the year,” Costello added.

The SPLC had previously tracked more than 800 incidents of “hateful harassment” across the U.S. since the Nov. 8 election.

Some of the teachers reported that recent incidents of harassment went unpunished by their schools, and about 40 percent said their schools had no apparent plan of action for dealing with them.

“I don’t think that they anticipated in any way what kids were going to say because for the most part, our schools are very diverse,” said one teacher from Kansas. “It’s not something we deal with anymore. It’s not like the ’50s, so this reactionary stuff going on just caught a lot of people by surprise.”

But Costello said the sharp uptick in less than two weeks since Trump’s election shows the problem must be seriously and swiftly addressed.

“There’s certainly been a breakdown in school culture and I think many schools are now ripe for incidents.”