Dozens of students were evacuated from Stimson Hall at Washington State University Monday night after students reported vandals had scratched several swastikas and a vague bomb threat onto dorm walls.

The graffiti was reported at about 10 p.m. Police inspected the building and found no evidence of explosives, and the students were allowed back in shortly after 2 a.m.

WSU assistant police chief Steve Hansen said the Nazi symbols were etched into walls in stairwells and common areas on multiple floors of the building. He said the markings were thin and hardly visible and appeared to have been created with a sharp knife.

He said the bomb threat was simply the word “bomb” above a time: 1 a.m.

Hansen, who’s been with WSU police since 1983, said the school has long received occasional, unsubstantiated bomb threats.

“Sometimes they’re written, sometimes they’re called in,” he said.

One such threat was received earlier this month.

The school also has grappled with issues of speech and racism during the past year. On Saturday, hundreds of students marched on campus to protest hate groups.

Last September, a student said she found racist graffiti on a desk in a WSU library – the N-word penciled above “TRUMP 2016.”

In February, fliers were found on the WSU campus urging people to report “illegal aliens” to immigration authorities. They appeared to be the work of a white supremacist group called American Vanguard.

And in a May, a racist video containing footage from a Donald Trump rally at WSU surfaced on social media, prompting an unsuccessful search for the person who created it.

“I’m hoping that this isn’t something that turns into a rash,” Hansen said.